A Study on Establishing Thermal Output Conditions of Radiant Ceiling Heating Panels for Improving Thermal Comfort of Perimeter Zone in Buildings

Amid concerns over airflow-induced transmission of the COVID-19 virus in buildings frequented by large numbers of people, such as offices, the necessity for radiant ceiling heating panels has increased. This is due to the concern that the airflows emitted from the convection heating systems installed near the ceiling or windows for winter heating may be a major cause of COVID-19 transmission. In this study, we aim to evaluate thermal comfort under various indoor and outdoor environmental conditions of a building and present the thermal output conditions of the radiant ceiling heating panel that can replace the convection heating system while ensuring comfort in the perimeter zone and handling the heating load. As a result, we were able to present, in a chart format, the thermal output conditions that can secure thermal comfort by analyzing the indoor airflow distribution depending on the surface temperature of the radiant ceiling heating panel, the interior surface temperature of the window, and the influence of internal heat generation. Moreover, through derived empirical formulas, we were able to determine the heating conditions of the panel that can secure the necessary heat dissipation while minimizing discomfort, such as downdrafts, even for indoor and outdoor conditions that were not evaluated in this study.

Large-eddy simulation of buoyant airflow in an airborne pathogen transmission scenario

Indoor airflow patterns and the spreading of respiratory air were studied using the large-eddy simulation (LES) computational fluid dynamics (CFD) approach. A large model room with mixing ventilation was investigated. The model setup was motivated by super-spreading of the SARS-CoV-2 virus with a particular focus on a known choir practice setup where one singer infected all the other choir members. The room was heated with radiators at two opposite walls in the cold winter time. The singers produced further heat generating buoyancy in the room. The Reynolds number of the inflow air jets was set to Re=2750, corresponding to an air-changes-per-hour (ACH) value of approximately 3.5. The CFD solver was first validated after which a thorough grid convergence study was performed for the full numerical model room with heat sources. The simulations were then executed over a time of t=20 min to account for slightly more than one air change timescale for three model cases: (1) full setup with heat sources (radiators+singers) in the winter scenario, (2) setup without radiators in a summer scenario, and (3) theoretical setup without buoyancy (uniform temperature). The main findings of the paper are as follows. First, the buoyant flow structures were noted to be significant. This was observed by comparing cases 1/2 with case 3. Second, the dispersion of the respiratory aerosol concentration, modeled as a passive scalar, was noted to be significantly affected by the buoyant flow structures in cases 1–2. In particular, the aerosol cloud was noted to either span the whole room (cases 1–2) or accumulate in the vicinity of the infected singer (case 3). Turbulence was clearly promoted by the interaction of the upward/downward moving warmer/cooler air currents which significantly affected the dispersion of the respiratory aerosols in the room. The study highlights the benefits of high-resolution, unsteady airflow modeling (e.g. LES) for interior design which may consequently also impact predictions on exposure to potentially infectious respiratory aerosols.

Improving Short-Term QPF Using Geostationary Satellite All-Sky Infrared Radiances: Real-Time Ensemble Data Assimilation and Forecast during the PRECIP 2020 and 2021 Experiments

The Prediction of Rainfall Extremes Campaign In the Pacific (PRECIP) aims to improve our understanding of extreme rainfall processes in the East Asian summer monsoon. A convection-permitting ensemble-based data assimilation and forecast system (the PSU WRF-EnKF system) was run in real time in the summers of 2020–21 in advance of the 2022 field campaign, assimilating all-sky infrared (IR) radiances from the geostationary Himawari-8 and GOES-16 satellites, and providing 48-h ensemble forecasts every day for weather briefings and discussions. This is the first time that all-sky IR data assimilation has been performed in a real-time forecast system at a convection-permitting resolution for several seasons. Compared with retrospective forecasts that exclude all-sky IR radiances, rainfall predictions are statistically significantly improved out to at least 4–6 h for the real-time forecasts, which is comparable to the time scale of improvements gained from assimilating observations from the dense ground-based Doppler weather radars. The assimilation of all-sky IR radiances also reduced the forecast errors of large-scale environments and helped to maintain a more reasonable ensemble spread compared with the counterpart experiments that did not assimilate all-sky IR radiances. The results indicate strong potential for improving routine short-term quantitative precipitation forecasts using these high-spatiotemporal-resolution satellite observations in the future.Significance StatementDuring the summers of 2020/21, the PSU WRF-EnKF data assimilation and forecast system was run in real time in advance of the 2022 Prediction of Rainfall Extremes Campaign In the Pacific (PRECIP), assimilating all-sky (clear-sky and cloudy) infrared radiances from geostationary satellites into a numerical weather prediction model and providing ensemble forecasts. This study presents the first-of-its-kind systematic evaluation of the impacts of assimilating all-sky infrared radiances on short-term qualitative precipitation forecasts using multiyear, multiregion, real-time ensemble forecasts. Results suggest that rainfall forecasts are improved out to at least 4–6 h with the assimilation of all-sky infrared radiances, comparable to the influence of assimilating radar observations, with benefits in forecasting large-scale environments and representing atmospheric uncertainties as well.

Assessing the impact of hyperviscosity on stenosis shape in COVID patients

Recent studies have proven that the shape of the stenosis greatly affects the flow characteristics. The 2D rigid wall model examined in this research is analyzed mathematically using various principles and results of functional analysis for the existence and uniqueness of the solution. The model taken into consideration for the current study has also been used to examine the consequences of hyperviscosity in COVID-19 cases. The results of the investigation surmise that the maximum peak velocity of 3.155m/s and the minimum trough pressure of 7041.538Pa were manifested in the high slope geometry. Also, the number of spots over the upper wall of high slope geometry bearing the least wall shear stress was considerably high when compared to the other geometries. The study deduced that the arterial segment bearing dual high slope stenosis was more susceptible to new plaques, plaque ruptures, and hyper viscous syndrome. © 2023 THE AUTHORS

POCT detection device based on thermal convection fluorescence PCR amplification

This article is based on the principle of thermal convection PCR and nucleic acid fluorescence intensity detection technology. The principle of thermal convection PCR is to form a temperature difference by separately controlling the upper temperature and the bottom temperature of the reaction tube. The lower temperature liquid at the upper part has relatively high density or specific gravity, and the upper and lower liquids will produce convection, which drives the flow of molecules in the tubular chamber. The reaction solution is formed into thermal convection in the reaction test tube and subjected to different temperatures, so as to meet the required conditions for the reaction of different enzymes, and realize the pre-denaturation, annealing and extension processes in the nucleic acid PCR amplification in a short time. Nucleic acid fluorescence intensity detection technology involves embedded system design for device control and signal analysis, optical system design for optical signal filtering and collection, and differential amplifier circuit design. The embedded system design is based on the development of precise temperature control system, motion system and signal analysis system based on Stm32 single-chip microcomputer. The temperature control system includes independent temperature control to control the heaters at the bottom of the reaction tube and the top of the reaction tube respectively;the motion system includes sample switching and switching of the light source in the imaging system. The optical system design includes 540nm FAM excitation light source, 570nm CY3 excitation light source and spherical lens focusing excitation system. This device uses a photodiode to convert the optical signal into an electrical signal, and then amplifies the collected electrical signal with a two-stage operational amplifier through a two-color light differential amplifier circuit, and then uses the signal analysis system to record and display the electrical signal changes in real time, and Make a qualitative analysis. This device not only has the advantages of low cost and high sensitivity, but also solves the key problem of the long time (more than 2 hours) of the whole process of real-time fluorescent quantitative PCR in the detection of new crown nucleic acid and cannot be screened quickly on site. The PCR time of this device is from 2 The hour is reduced to 30 minutes, which is suitable for POCT inspections, and achieves rapid screening goals for crowds of people, which is conducive to responding to acute nucleic acid detection and large-scale nucleic acid detection. This device is currently used with COVID-19 detection reagents to detect new coronaviruses, and realize the detection of 20 copies of nucleic acid sensitivity within 30 minutes. Four samples can be processed in batches at a time, and the sample size for single processing can be increased appropriately according to needs. This device provides rapid and sensitive screening methods for global epidemic prevention and control, and is of great significance to improve human health. This device can also be applied to other rapid nucleic acid detection fields. With different nucleic acid detection reagents, this device can detect different gene loci, and has a broad development space and application fields. © 2023 SPIE.

The Met Office winter testbed 2020/2021: Experimenting with an on-demand 300-m ensemble in a real-time environment

The Met Office held a testbed over winter 2020/2021 where a new numerical weather prediction (NWP) sub-km ensemble was set up on-demand in response to interesting weather phenomena in the United Kingdom. The domain for the model was chosen in real time by a community of Met Office Research Scientists and Operational Meteorologists and over a 4-month period the ensemble was triggered for nine events. The purpose of the testbed was to investigate whether a real-time weather regime-based enhancement in NWP capability was feasible, to understand what benefits a testbed environment might give, and to explore the practicalities of running such an event. Case studies from the testbed demonstrated that forecast ensembles at 2.2 km and 300 m grid spacing were able to capture observed winter weather, with greater spatial detail apparent, especially over complex orography, in the 300-m model. Ensemble spread appeared less influenced by resolution, potentially due to the size of the domains tested or the weather regimes of the case studies. The testbed also showcased underutilized observations and additional radiosonde ascents were conducted. All the testbed meetings were conducted virtually due to COVID-19 restrictions, and decisions were made about when to trigger the event using an online message board. The winter 2020/2021 testbed provides ideas for how on-demand weather-dependent testbeds might be conducted in the future. However, several recommendations are made that would enhance testbed benefits further, including more dedicated resource, stronger technology and data visualization and greater participation from both academia and weather information users.

HEATQUIZ: AN OPEN-ACCESS FRAMEWORK FOR HEAT TRANSFER EDUCATION WITH GAME-BASED LEARNING ELEMENTS

Since 2017, HeatQuiz is developed as a tool for students in the subject of Heat and Mass Transfer to train their skills and strengthen their knowledge. The topics span from view factors to temperature distributions up to dimensionless numbers. With more that 800 questions, HeatQuiz provides a large variety of questions in it's database. Due to the COVID-19 pandemic and the obligation for social distancing HeatQuiz has evolved from a mobile teaching application with customized subject-specific question types to a tool that combines game-based elements with structured access to an open heat transfer lecture. Combining micro-lectures for the flipped-classroom concept and hundreds of quiz questions in a well structured learning environment is one of the main strengths. This article describes the learning path concept and how it is embedded in HeatQuiz. Secondly, a new question type will be introduced that is especially designed to practise the skill of developing energy balances based on a sketch of the control volume, defining all relevant fluxes, and finally defining the required boundary conditions. © 2022 Begell House Inc.. All rights reserved.

Penetration Efficiency and Concentration Distribution of Nanoparticles in a Hollow Tapered Cylinder

Knowing particle penetration efficiencies and concentration distributions in an inlet channel of a sampling device is beneficial for the robust assessment, attribution and quantification of nanoparticles produced by various activities. The aim of this research is to evaluate the effect of the presence or absence of a conical column inside a hollow tapered cylinder on the nanoparticle penetration efficiency and its outlet concentration profile for different flow rates. The particle penetration characteristics of various sizes from 3 nm to 20 nm were numerically investigated by using the flow field and convection diffusion equations within the hollow tapered cylinder. Firstly, the proposed model of the nanoparticle penetration efficiency for the hollow tapered cylinder with the conical column is validated with the experimental data in the literature. Then, the results indicate that the concentration at the outlet of the hollow tapered cylinder with the conical column exhibits annular profiles for 3 nm and 5 nm nanoparticles at a flow rate of 2.0 L/min, which is found to avoid centralizing the particles in the exit area. In addition, the penetration efficiency of nanoparticles can be improved by increasing flow rates or removing the conical column inside the hollow tapered cylinder. Finally, the ring-shaped concentration profile of the 10 nm nanoparticles at the outlet of the hollow conical cylinder with the conical column becomes more obvious as the flow rate decreases. This study interprets and quantitatively decides the nanoparticle penetration efficiency and its exit concentration profile for the hollow tapered cylinder with or without the conical column. Therefore, the results can provide some useful design references for the transport of nanoparticles in the hollow tapered cylinder.

Research on Wire-to-Two Fin Configuration for Positive Atmospheric Plasma by Electrokinetic Blower

Interest in the development of electro-fluid-dynamic devices (EFDs) based on corona discharge is growing due to their advantages and applicability across different industrial sectors. On the one hand, their performance as forced convection motors, in terms of weight, volume, and absence of noise and moving parts, make them competitive against traditional systems such as fans. On the other hand, the actions of the corona discharge, in terms of elimination of viruses and bacteria, are already known. This paper studies the characteristics of corona discharge in terms of air flow for a new proposed configuration and geometry of electrodes. A systematic study is performed through a parametric study of the distances, power consumption, and size of the corona electrode. The characteristic voltage–current (CVCCs) and flow–pressure curves obtained provide design rules to use the generated corona discharge and the device itself, as a silent air propeller, which may also sterilize the surrounding environment and surfaces.

Progress and Challenges in Modeling Dynamics–Microphysics Interactions: From the Pi Chamber to Monsoon Convection

The CAIPEEX (Cloud Aerosol Interaction and Precipitation Enhancement Experiment) monsoon convective clouds case was designed to explore the impacts of environmental and cloud condensation nuclei (CCN) conditions on monsoon convection. Pi chamber warm cloud case The scientific objectives are 1) to demonstrate the model capability of representing the detailed microphysical processes happening in the cloud chamber and how different models behave in different aerosol injection rates, 2) to reveal the model uncertainties and limitations in the existing modeling tools, and 3) to provide guidance and recommendations for future work to improve cloud chamber simulations and model–laboratory comparisons. The comparison was performed among a diverse set of model categories, including four types of LES models (Dziekan et al. 2019;Shima et al. 2009, 2020;Niedermeier et al. 2020;Khairoutdinov and Randall 2003) performed by the University of Warsaw, University of Hyogo, Leibniz Institute for Tropospheric Research, and Brookhaven National Laboratory;two types of direct numerical simulation (DNS) models (Chen et al. 2021;Richter et al. 2021) by the National Center for Atmospheric Research (NCAR) and the University of Notre Dame;and the Linear Eddy Model (LEM;Su et al. 1998) by the University of Utah. Interestingly, however, the amount of updraft tilting was sensitive not only to the vertical wind shear used in the model, but also to the method of cloud initiation, i.e., forcing using warm bubbles or surface heat fluxes.

Convection-Permitting Models for Climate Research

4th International Convection-Permitting Modeling Workshop for Climate Research What: The purpose of the workshop was to discuss the performance of convection-permitting models (<4-km horizontal grid spacing) at global and local scales and also to discuss the potential of CPMs data for hazard and impact studies. Because of the rapid development of the convection-permitting modeling (CPM) field, we felt the need to host a virtual workshop this year to maintain community interactions and to provide a forum where scientific advances are presented and discussed. [...]the use of satellite observations and targeted model experiments that make use of field campaign data were discussed for evaluating global CPMs. High-resolution and high-quality observations were identified as crucial for a better understanding of processes and phenomena that cause extreme events and for supporting the development of parameterization schemes. Since rainfall is expected to intensify at small spatial and temporal scales in future climates, the impact of precipitation on the initiation of landslides in small river catchments becomes increasingly important.

Harmonization and Verification of Three National European Icing Forecast Models Using Pilot Reports

The Single European Sky Air Traffic Management Research (SESAR) program aims at modernizing and harmonizing the European airspace, which currently has a strongly fragmented character. Besides turbulence and convection, in-flight icing is part of SESAR and can be seen as one of the most important meteorological phenomena, which may lead to hazardous flight conditions for aircraft. In this study, several methods with varying complexities are analyzed for combining three individual in-flight icing forecasts based on numerical weather prediction models from Deutscher Wetterdienst, Météo-France, and Met Office. The optimal method will then be used to operate one single harmonized in-flight icing forecast over Europe. As verification data, pilot reports (PIREPs) are used, which provide information about hazardous weather and are currently the only direct regular measure of in-flight icing events available. In order to assess the individual icing forecasts and the resulting combinations, the probability of detection skill score is calculated based on multicategory contingency tables for the forecast icing intensities. The scores are merged into a single skill score to give an overview of the quality of the icing forecast and enable comparison of the different model combination approaches. The concluding results show that the most complex combination approach, which uses iteratively optimized weighting factors for each model, provides the best forecast quality according to the PIREPs. The combination of the three icing forecasts results in a harmonized icing forecast that exceeds the skill of each individual icing forecast, thus providing an improvement to in-flight icing forecasts over Europe.

SARS-CoV-2 Dynamics in the Mucus Layer of the Human Upper Respiratory Tract Based on Host–Cell Dynamics

A thorough understanding of the inhalation dynamics of infectious aerosols indoors and infection dynamics within the host by inhaled viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays an important role in the assessment and control of infection risks indoors. Here, by combining computational fluid–particle dynamics (CFPD) and host–cell dynamics (HCD), SARS-CoV-2 infection dynamics in the mucus layer of the human upper airway were studied. To reproduce the diffusive and convective transport of the virus in the nasal cavity–nasopharynx by mucociliary motion, a three-dimensional (3D)-shell model with a mucus layer was developed. The initial virus concentrations for HCD calculation were estimated based on the deposition distribution of droplets with representative sizes analyzed by CFPD. To develop a new HCD model, the target-cell-limited model was integrated with the convection–diffusion equation. Additionally, the sensitivity of the infection rate β to the infection dynamics was systematically investigated. The results showed that the time series of SARS-CoV-2 concentration in the mucus layer strongly depended on diffusion, convection, and β. Although the SARS-CoV-2 dynamics obtained here have not been verified by corresponding clinical data, they can preliminarily reveal its transmission mode in the upper airway, which will contribute to the prevention and treatment of coronavirus disease 2019.

Sneezing Aerosol Transport in an Indoor Farmers’ Market

The transportation and surface deposition of aerosols from sneezing in a small indoor farmers’ market are studied numerically. The effects of numbers and locations of the entrances and exits of the market are discussed under the condition of natural convection. The results indicate that aerosols leave the indoor environment more quickly when two doors are designed face to face on the walls perpendicular to the natural wind direction compared to other natural ventilation strategies. The concentrations of aerosols accumulated on the surfaces of the stalls and human bodies inside the market are also lower. In this case, the risk of contacting the virus is relatively low among susceptible individuals in the indoor farmers’ markets. Moreover, opening more doors on the walls parallel to the natural wind direction is not beneficial for the fast exhaust of aerosols.

Computational Study of Thermal Comfort and Reduction of CO2 Levels inside a Classroom.

Due to the current COVID-19 pandemic, guaranteeing thermal comfort and low CO2 levels in classrooms through efficient ventilation has become vitally important. This study presents three-dimensional simulations based on computational fluid dynamics of airflow inside an air-conditioned classroom located in Veracruz, Mexico. The analysis included various positions of an air extractor, Reynolds numbers up to 3.5 × 104, four different concentrations of pollutant sources, and three different times of the day. The simulations produced velocity, air temperature, and CO2 concentrations fields, and we calculated average air temperatures, average CO2 concentrations, and overall ventilation effectiveness. Our results revealed an optimal extractor position and Reynolds number conducive to thermal comfort and low CO2 levels due to an adequate ventilation configuration. At high pollutant concentrations, it is necessary to reduce the number of students in the classroom to achieve safe CO2 levels.

Generalized Mittag-Leffler Kernel Form Solutions of Free Convection Heat and Mass Transfer Flow of Maxwell Fluid with Newtonian Heating: Prabhakar Fractional Derivative Approach

In this article, the effects of Newtonian heating along with wall slip condition on temperature is critically examined on unsteady magnetohydrodynamic (MHD) flows of Prabhakar-like non integer Maxwell fluid near an infinitely vertical plate under constant concentration. For the sake of generalized memory effects, a new mathematical fractional model is formulated based on a newly introduced Prabhakar fractional operator with generalized Fourier’s law and Fick’s law. This fractional model has been solved analytically and exact solutions for dimensionless velocity, concentration, and energy equations are calculated in terms of Mittag-Leffler functions by employing the Laplace transformation method. Physical impacts of different parameters such as α, Pr, β, Sc, Gr, γ, and Gm are studied and demonstrated graphically by Mathcad software. Furthermore, to validate our current results, some limiting models such as classical Maxwell model, classical Newtonian model, and fractional Newtonian model are recovered from Prabhakar fractional Maxwell fluid. Moreover, we compare the results between Maxwell and Newtonian fluids for both fractional and classical cases with and without slip conditions, showing that the movement of the Maxwell fluid is faster than viscous fluid. Additionally, it is visualized that both classical Maxwell and viscous fluid have relatively higher velocity as compared to fractional Maxwell and viscous fluid.

Convective polymerase chain reaction in standard microtubes.

Polymerase chain reaction (PCR) is the most widely used method for nucleic acids amplification. To date, a huge number of versatile PCR techniques have been developed. One of the relevant goals is to shorten PCR duration, which can be achieved in several ways. Here, we report on the results regarding nucleic acids amplification by convective PCR (cPCR) in standard 0.2 ml polypropylene microtubes. The following conditions were found to be optimal for such amplification: 1) 70 µl reaction volume, 2) the supply of external temperature 145°Ð¡ for the denaturation zone and 0°Ð¡ for the annealing zone, 3) ∼30° inclination of the microtube main axis, 4) the use of nearby primers, and 5) duration of the reaction 15-20 min. At these conditions, the amplification products are accumulated in an amount sufficient to be registered by gel electrophoresis, and high sensitivity of the reaction comparable to that of conventional PCR is achieved. cPCR provided the reliable detection of SARS-CoV-2 coronavirus RNA isolated from nasopharyngeal swabs of COVID-19 patients.

Virions and respiratory droplets in air: Diffusion, drift, and contact with the epithelium.

Some infections, including e.g. influenza and currently active COVID 19, may be transmitted via air during sneezing, coughing, and talking. This pathway occurs via diffusion and gravity-induced drift of single virions and respiratory droplets consisting primarily of water, including small fraction of nonvolatile matter, and containing virions. These processes are accompanied by water evaporation resulting in reduction of the droplet size. The manifold of information concerning these steps is presented in textbooks and articles not related to virology and the focus is there frequently on biologically irrelevant conditions and/or droplet sizes. In this brief review, we systematically describe the behavior of virions and virion-carrying droplets in air with emphasis on various regimes of diffusion, drift, and evaporation, and estimate the rates of all these steps under virologically relevant conditions. In addition, we discuss the kinetic aspects of the first steps of infection after attachment of virions or virion-carrying droplets to the epithelium, i.e., virion diffusion in the mucus and periciliary layers, penetration into the cells, and the early stage of replication. The presentation is oriented to virologists who are interested in the corresponding physics and to physicists who are interested in application of the physics to virology.

Electric fans: A potential stay-at-home cooling strategy during the COVID-19 pandemic this summer?

Current public health guidance designed to protect individuals against extreme heat and the ongoing COVID-19 pandemic is seemingly discordant, yet during the northern hemisphere summer, we are faced with the imminent threat of their simultaneous existence. Here we examine the environmental limits of electric fan-use in the context of the United States summer as a potential stay-at-home cooling strategy that aligns with existing efforts to mitigate the spread of SARS-COV-2.