scholarly journals A simplified model to estimate COVID19 transport in enclosed spaces

2021 ◽  
Vol 2069 (1) ◽  
pp. 012191
Author(s):  
P A Mirzaei ◽  
M Moshfeghi ◽  
H Motamedi ◽  
Y Sheikhnejad ◽  
H Bordbar
Keyword(s):  
Disease Transmission ◽  
Thermal Conditions ◽  
Source Model ◽  
Simplified Model ◽  
Release Mechanism ◽  
Cfd Model ◽  
Computational Framework ◽  
Infected People ◽  
Spread Model ◽  
Enclosed Space

Abstract Airborne pathogen respiratory droplets are the primary route of COVID19 transmission, which are released from infected people. The strength and amplitude of a release mechanism strongly depend on the source mode, including respiration, speech, sneeze, and cough. This study aims to develop a simplified model for evaluation of spreading range (length) in sneeze and cough modes using the results of Eulerian-Lagrangian CFD model. The Eulerian computational framework is first validated with experimental data, and then a high-fidelity Lagrangian CFD model is employed to monitor various scale particles’ trajectory, evaporation, and lingering persistency. A series of Eulerian-Lagrangian CFD simulations is conducted to generate a database of bioaerosol release spectrum for the release modes in various thermal conditions of an enclosed space. Eventually, a correlation fitted over the data to offer a simplified airborne pathogen spread model. The simplified model can be applied as a source model for design and decision-making about ventilation systems, occupancy thresholds, and disease transmission risks in enclosed spaces.

scholarly journals Modeling quarantine during epidemics and mass-testing using drones

2020 ◽  
Author(s):  
Leonid Sedov ◽  
Alexander Krasnochub ◽  
Valentin Polishchuk
Keyword(s):  
Differential Equations ◽  
Metropolitan Area ◽  
Extended Model ◽  
Epidemic Spread ◽  
Infected People ◽  
Peak Number ◽  
Infected Population ◽  
Sir Epidemic ◽  
Spread Model ◽  
Over Time

We extend the classical SIR epidemic spread model by introducing the “quarantined” compartment. We solve (numerically) the differential equations that govern the extended model and quantify how quarantining “flattens the curve” for the proportion of infected population over time. Furthermore, we explore the potential of using drones to deliver tests, enabling mass-testing for the infection; we give a method to estimate the drone fleet needed to deliver the tests in a metropolitan area. Application of our models to COVID-19 spread in Sweden shows how the proposed methods could substantially decrease the peak number of infected people, almost without increasing the duration of the epidemic.

scholarly journals Irradiation Flux Modelling for Thermal–Electrical Simulation of CubeSats: Orbit, Attitude and Radiation Integration

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6691
Author(s):  
Edemar Morsch Filho ◽  
Laio Oriel Seman ◽  
Cezar Antônio Rigo ◽  
Vicente de Paulo Nicolau ◽  
Raúl García Ovejero ◽  
...  
Keyword(s):  
Good Practice ◽  
Thermal Conditions ◽  
Source Model ◽  
Hardware In The Loop ◽  
Loop Analysis ◽  
Input Estimation ◽  
The Earth ◽  
Software And Hardware ◽  
Element Set

During satellite development, engineers need to simulate and understand the satellite’s behavior in orbit and minimize failures or inadequate satellite operation. In this sense, one crucial assessment is the irradiance field, which impacts, for example, the power generation through the photovoltaic cells, as well as rules the satellite’s thermal conditions. This good practice is also valid for CubeSat projects. This paper presents a numerical tool to explore typical irradiation scenarios for CubeSat missions by combining state-of-the-art models. Such a tool can provide the input estimation for software and hardware in the loop analysis for a given initial condition and predict it along with the satellite’s lifespan. Three main models will be considered to estimate the irradiation flux over a CubeSat, namely an orbit, an attitude, and a radiation source model, including solar, albedo, and infrared emitted by the Earth. A case study illustrating the tool’s abilities is presented for a typical CubeSats’ two-line element set (TLE) and five attitudes. Finally, a possible application of the tool as an input to a CubeSat task-scheduling is introduced. The results show that the complete model’s use has considerable differences from the simplified models sometimes used in the literature.

Numerical Simulation of Tsunami Run-Up and Inundation for the 2011 Tōhuku-Oki Tsunami: A Parametric Analysis for Tsunami Run-Up and Wave Height

2014 ◽  
Author(s):  
Debashis Basu ◽  
Robert Sewell ◽  
Kaushik Das ◽  
Ron Janetzke ◽  
Biswajit Dasgupta ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Wave Height ◽  
Seismic Waves ◽  
Source Model ◽  
Tsunami Source ◽  
Computational Framework ◽  
Wave Amplification ◽  
Source Models ◽  
Run Up ◽  
Tsunami Run Up

This paper presents computational results for predicting earthquake-generated tsunami from a developed integrated computational framework. The computational framework encompasses the entire spectrum of modeling the earthquake-generated tsunami source, open-sea wave propagation, and wave run-up including inundation and on-shore effects. The present work develops a simplified source model based on pertinent local geologic and tectonic processes, observed seismic data (i.e., data obtained by inversion of seismic waves from seismographic measurements), and geodetic data (i.e., directly measured seafloor and land deformations). These source models estimated configurations of seafloor deformation used as initial waveforms in tsunami simulations. Together with sufficiently accurate and resolved bathymetric and topographic data, they provided the inputs needed to numerically simulate tsunami wave propagation, inundation and coastal impact. The present work systematically analyzes the effect of the tsunami source model on predicted tsunami behavior and the associated variability for the 2011 Tōhuku-Oki tsunami. Simulations were carried out for the 2011 Tōhuku -Oki Tsunami that took place on March 11, 2011, from an MW 9.1 earthquake. The numerical simulations were performed using the fully nonlinear Boussinesq hydrodynamics code, FUNWAVE-TVD (distributed by the University of Delaware). In addition, a sensitivity analysis was also carried out to study the effect of earthquake magnitude on the predicted wave height. The effect of coastal structure on the wave amplification at the shore is also studied. Simulated tsunami results for wave heights are compared to the available observational data from GPS (Global Positioning System) at the central Miyagi location.

scholarly journals A SIMPLE NOISE MODEL WITH MEMORY FOR BIOLOGICAL SYSTEMS

2005 ◽  
Vol 05 (02) ◽  
pp. L243-L250 ◽  
Author(s):  
O. CHICHIGINA ◽  
D. VALENTI ◽  
B. SPAGNOLO
Keyword(s):  
Noise Source ◽  
Pulse Sequence ◽  
Biological Systems ◽  
Source Model ◽  
Noise Model ◽  
Time Behavior ◽  
Correlated Noise ◽  
Infected People ◽  
Random Times ◽  
With Memory

A noise source model, consisting of a pulse sequence at random times with memory, is presented. By varying the memory we can obtain variable randomness of the stochastic process. The delay time between pulses, i.e. the noise memory, produces different kinds of correlated noise ranging from white noise, without delay, to quasi-periodical process, with delay close to the average period of the pulses. The spectral density is calculated. This type of noise could be useful to describe physical and biological systems where some delay is present. In particular it could be useful in population dynamics. A simple dynamical model for epidemiological infection with this noise source is presented. We find that the time behavior of the illness depends on the noise parameters. Specifically the amplitude and the memory of the noise affect the number of infected people.

Improved Computational Fluid Dynamics Model for Open-Aisle Air-Cooled Data Center Simulations

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Waleed A. Abdelmaksoud ◽  
Thong Q. Dang ◽  
H. Ezzat Khalifa ◽  
Roger R. Schmidt
Keyword(s):  
High Power ◽  
Data Center ◽  
Large Scale ◽  
Source Model ◽  
Cfd Modeling ◽  
Small Data ◽  
Cfd Model ◽  
It Industry ◽  
Cfd Models ◽  
Tile Flow

There is a need in the IT industry for CFD models that are capable of accurately predicting the thermal distributions in high power density open-aisle air-cooled data centers for use in the design of these facilities with reduced cooling needs. A recent detailed evaluation of a small data center cell equipped with one high power rack using current CFD practice showed that the CFD results were not accurate. The simulation results exhibited pronounced hot/cold spots in the data center while the test data were much more diffused, indicating that the CFD model under-predicted the mixing process between the cold tile flow and the hot rack exhaust flow with the warm room air. In this study, a parametric study was carried out to identify CFD modeling issues that contributed to this error. Through a combined experimental and computational investigation, it was found that the boundary condition imposed at the perforated surfaces (e.g., perforated tiles and rack exhaust door) as fully open surfaces was the main source of error. This method enforces the correct mass flux but the initial jet momentum is under-specified. A momentum source model proposed for these perforated surfaces is found to improve the CFD results significantly. Another CFD modeling refinement shown to improve CFD predictions is the inclusion of some large-scale geometrical features of the perforated surfaces (e.g., lands/gaps) in the CFD model, but this refinement requires the use of grids finer than those typically used in practice.

scholarly journals Controlling COVID-19 Outbreaks with Financial Incentives

2021 ◽  
Vol 18 (2) ◽  
pp. 724
Author(s):  
Chaeyoung Lee ◽  
Soobin Kwak ◽  
Junseok Kim
Keyword(s):  
Disease Transmission ◽  
Financial Incentives ◽  
Transmission Rate ◽  
Economic Losses ◽  
Total Cost ◽  
Infected People ◽  
Infected Population ◽  
Estimated Parameters ◽  
Two Parameters ◽  
Termination Time

In this paper, we consider controlling coronavirus disease 2019 (COVID-19) outbreaks with financial incentives. We use the recently developed susceptible-unidentified infected-confirmed (SUC) epidemic model. The unidentified infected population is defined as the infected people who are not yet identified and isolated and can spread the disease to susceptible individuals. It is important to quickly identify and isolate infected people among the unidentified infected population to prevent the infectious disease from spreading. Considering financial incentives as a strategy to control the spread of disease, we predict the effect of the strategy through a mathematical model. Although incentive costs are required, the duration of the disease can be shortened. First, we estimate the unidentified infected cases of COVID-19 in South Korea using the SUC model, and compute two parameters such as the disease transmission rate and the inverse of the average time for confirming infected individuals. We assume that when financial incentives are provided, there are changes in the proportion of confirmed patients out of unidentified infected people in the SUC model. We evaluate the numbers of confirmed and unidentified infected cases with respect to one parameter while fixing the other estimated parameters. We investigate the effect of the incentives on the termination time of the spread of the disease. The larger the incentive budget is, the faster the epidemic will end. Therefore, financial incentives can have the advantage of reducing the total cost required to prevent the spread of the disease, treat confirmed patients, and recover overall economic losses.

scholarly journals Malaria in Southern Venezuela: The Hottest Hotspot in Latin America

2020 ◽  
Author(s):  
ME Grillet ◽  
JE Moreno ◽  
JV Hernández ◽  
MF Vincenti-González ◽  
O Noya ◽  
...  
Keyword(s):  
Latin America ◽  
Malaria Transmission ◽  
Disease Transmission ◽  
Epidemiological Data ◽  
Infected People ◽  
International Borders ◽  
Border Malaria ◽  
Source Sink ◽  
Latin America Region

AbstractMalaria cases in Latin America reached ~1 million in 2017 and 2018, with 53% and 51% reported from Venezuela, respectively. In this study, we characterized the spatiotemporal dynamics of malaria transmission between 2007-2017 in southern Venezuela, the main endemic area of the country. We found that disease transmission was focal and more prevalent in the southeast of southern Venezuela where two persistent hotspots of Plasmodium vivax (76%) and P. falciparum (18%) linked to deforestation for illegal gold mining accounted for ~60% of the country-wide number of cases. Incidence has increased nearly tenfold in the last decade, showing an explosive epidemic growth due to a significant lack of disease control. We suggest that a source-sink pattern of Plasmodium sp. dispersal account for the re-emergence and progression of malaria transmission in the last 4 years across the country due to the internal migration of infected people to and from the hotspots and other malaria-prone ecosystems. We observe a similar pattern explaining the spillover of cases across international borders affecting neighboring countries. This study provides baseline epidemiological data and guidance for malaria control to further assess the dynamics of cross-border malaria, the role of asymptomatic carriers, drug-resistant evolution, and innovative control efforts in the Latin America region.

scholarly journals A Computational Framework for Transmission Risk Assessment of Aerosolized Particles in Classrooms

2021 ◽  
Author(s):  
Kendrick Tan ◽  
Boshun Gao ◽  
Cheng-Hau Yang ◽  
Emily Johnson ◽  
Ming-Chen Hsu ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Disease Transmission ◽  
Ventilation Rate ◽  
Mitigation Strategies ◽  
Transmission Risk ◽  
Computational Framework ◽  
Seating Arrangement ◽  
K 12 ◽  
Education Administrators ◽  
Airborne Disease

Abstract The ongoing COVID-19 pandemic has rendered confined spaces as high-risk areas. There is an increasing push to resume in-person activities, for instance, teaching in K-12 and university settings. It becomes important to evaluate the risk of airborne disease transmission while accounting for the physical presence of humans, furniture, and electronic equipment, as well as ventilation. Here, we present a computational framework based on detailed flow physics simulations that allows straightforward evaluation of various seating and operating scenarios to identify risk factors and assess the effectiveness of various mitigation strategies. These scenarios include seating arrangement changes, presence/absence of computer screens, ventilation rate changes, and presence/absence of mask-wearing. This approach democratizes risk assessment by automating a key bottleneck in simulation-based analysis--creating an adequately refined mesh around multiple complex geometries. Not surprisingly, we find that wearing masks (with at least 74% inward protection efficiency) significantly reduced transmission risk against unmasked and infected individuals. The availability of such an analysis approach will allow education administrators, government officials (courthouses, police stations), and hospital administrators to make informed decisions on seating arrangements and operating procedures.

Numerical modelling of fire test with timber fire protection

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Vojtěch Šálek ◽  
Kamila Cábová ◽  
František Wald ◽  
Milan Jahoda
Keyword(s):  
Experimental Data ◽  
Material Properties ◽  
Fire Test ◽  
Fire Spread ◽  
Test Facility ◽  
Simplified Model ◽  
Cfd Model ◽  
Temperature Dependent ◽  
Content Type ◽  
Room Corner Test

PurposeThe purpose of this paper is to present a complex pyrolysis computational fluid dynamics (CFD) model of timber protection exposed to fire in a medium size enclosure. An emphasis is placed on rarely used temperature-dependent thermal material properties effecting the overall simulation outputs. Using the input dataset, a fire test model with oriented strand boards (OSB) in the room corner test facility is created in Fire Dynamics Simulator (FDS).Design/methodology/approachSeven FDS models comprising different complexity approaches to modelling the burning of wood-based materials, from a simplified model of burning based on a prescribed heat release rate to complex pyrolysis models which can describe the fire spread, are presented. The models are validated by the experimental data measured during a fire test of OSB in the room corner test facility.FindingsThe use of complex pyrolysis approach is recommended in real-scale enclosure fire scenarios with timber as a supplementary heat source. However, extra attention should be paid to burning material thermal properties implementation. A commonly used constant specific heat capacity and thermal conductivity provided poor agreement with experimental data. When the fire spread is expected, simplified model results should be processed with great care and the user should be aware of possible significant errors.Originality/valueThis paper brings an innovative and rarely used complex pyrolysis CFD model approach to predict the behaviour of timber protection exposed to fire. A study on different temperature-dependent thermal material properties combined with multi-step pyrolysis in the room corner test scenario has not been sufficiently published and validated yet.

Examination of operational dynamics of radiant ceiling panel

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Edyta Dudkiewicz ◽  
Piotr Jadwiszczak ◽  
Janusz Jeżowiecki
Keyword(s):  
Automatic Control ◽  
Thermal Effects ◽  
Thermal Conditions ◽  
Cooling Power ◽  
Control Loops ◽  
Control Programs ◽  
Small Water ◽  
Radiant Panel ◽  
Enclosed Space ◽  
Feeding Medium

AbstractRadiant ceiling panels can be used in large-volume halls, e.g. vehicle repair shops and markets, to heat the entire or specific zones of the enclosed space. The system with radiant panels may be of small water capacity when just one or several units are installed over selected zones to provide additional heating. Depending on dimensions of radiant ceiling panel, its mounting mode and the temperature of its feeding medium, various thermal conditions are created under such panel. Thermal effects are also affected by the mode of thermal or cooling power control and dynamics of such control for an individual radiant panel or a set of panels. The dynamics of attainable radiant ceiling panel capacity was investigated and used as the grounds to determine general requirements for time-domain automatic control programs and those for operation of the controllers. The results presented from the examinations carried out for water radiators are not intended to delineate the requirements for all automatic control loops for water radiators; they are aimed at attracting attention to issues to be considered when preparing the algorithm of automatic control in particular situations.

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