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Indoor air quality is critical for human health, and as such, it must be continuously improved. As a result, it is critical to identify the factors influencing indoor air quality. In this context, the purpose of this study is to investigate the factors influencing indoor air quality and to conduct a bibliometric analysis of the studies on the subject. The method of bibliometric analysis was used to examine academic publications on indoor air quality published between 1975 and 2020. A total of 2398 academic studies from the Web of Science database were examined. According to the findings of the analyses, academic research has primarily been conducted in the fields of construction technology and environmental sciences, public environmental occupational health, and environmental engineering. Since 2010, there has been a significant increase in the number of publications. The year with the most publications was 2017, and especially after 2010, publications have been cited more and more. One-fourth of the publications were produced solely in the United States. Hong Kong Polytechnic University and Denmark Technical University had the most publications. It has been determined that ventilation and air flow rate are the most heavily researched factors affecting indoor air quality. On the other hand, a substantial amount of research has been conducted to investigate the effects of pollutants. Furthermore, publications on temperature, humidity, bacteria, and thermal comfort were discovered. There have been studies on indoor air quality in residential buildings, houses, schools, and hospitals. [ABSTRACT FROM AUTHOR]

Model‐estimated monthly water balance components (i.e., potential evapotranspiration, actual evapotranspiration, and runoff (R)) for 146 United States (U.S.) Geological Survey 8‐digit hydrologic units located in the Colorado River Basin (CRB) are used to examine the temporal and spatial variability of the CRB water balance for water years 1901 through 2014 (a water year is the period from October 1 of one year through September 30 of the following year). Results indicate that the CRB can be divided into six subregions with similar temporal variability in monthly R. The water balance analyses indicated that approximately 75% of total water‐year R is generated by just one CRB subregion and that most of the R in the basin is derived from surplus (S) water generated during the months of October through April. Furthermore, the analyses show that temporal variability in S is largely controlled by the occurrence of negative atmospheric pressure anomalies over the northwestern conterminous U.S. (CONUS) and positive atmospheric pressure anomalies over the southeastern CONUS. This combination of atmospheric pressure anomalies results in an anomalous flow of moist air from the North Pacific Ocean into the CRB, particularly the Upper CRB. Additionally, the occurrence of extreme dry and wet periods in the CRB appears to be related to variability of the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation. Research Impact Statement: A comprehensive evaluation of the variability of the water balance of the Colorado River Basin (CRB) is presented that has potential implications for water supply management in the CRB. [ABSTRACT FROM AUTHOR]

Model estimated monthly water balance (WB) components (i.e., potential evapotranspiration, actual evapotranspiration, and runoff [R]) for 848 United States (U.S.) Geological Survey 8‐digit hydrologic units located in the Mississippi River Basin (MRB) are used to examine the temporal and spatial variability of the MRB WB for water years 1901 through 2014. Results indicate the MRB can be divided into nine subregions with similar temporal variability in R. The WB analyses indicated ~79% of total water‐year MRB runoff is generated by four of the nine subregions and most of the R in the basin is derived from surplus (S) water during the months of December through May. Furthermore, the analyses showed temporal variability in S is largely controlled by the occurrence of negative atmospheric pressure anomalies over the western U.S. and positive atmospheric pressure anomalies over the eastern U.S. coast. This combination of atmospheric pressure anomalies results in an anomalous flow of moist air from the Gulf of Mexico into the MRB. In the context of paleo‐climate reconstructions of the Palmer Drought Severity Index, since about 1900 the MRB has experienced wetter conditions than were experienced during the previous 500 years. Research Impact Statement: This study provides a baseline understanding of the hydroclimatology of the Mississippi River Basin (MRB) and can be used to guide the selection of regions within the MRB for targeted analyses. [ABSTRACT FROM AUTHOR]

Buildings account for about 39% of the total energy consumption in the United States. Developing highly energy-efficient and environmentally friendly systems that are either actively or passively integrated into buildings plays a crucial role in decarbonizing the building sector. Among various technologies, desiccant-based energy systems have received particular attention in recent years due to their unique advantages, such as being thermally driven using low-grade waste or solar energies and being reliable over a wide range of operating ranges. Extensive research efforts have been exerted on desiccant-enabled technologies at both material and system levels aiming to increase their performance and achieve high technological readiness levels. The present review paper comprehensively discusses research works made at the system level. It overviews desiccant-based air conditioning systems, desiccant-based humidity pumps, desiccant-based thermal energy storage systems, and desiccant-based appliances. The study identifies challenges and opportunities to accelerate the commercialization of desiccant-enabled technologies. It is found that desiccant materials offer great promise to improve energy efficiency and functionality of future buildings through decoupling the latent and sensible cooling loads in air conditioning systems, humidity pumps integrated into building facades, and next-generation appliances. However, commercial viability and widespread acceptance of desiccant-based systems have been hampered by several major obstacles, including liquid and air flow mal-distribution and inferior thermo-physical properties of desiccant materials resulting in low ab/adsorption and regeneration rates and bulky/costly systems. • Review the desiccant-enabled technologies at the system level. • Traditional desiccants suffer from limited performance in low-humid climates. • Humidity pumps integrate desiccants into the building facade. • Desiccant materials are promising for clothes dryers and dishwashers. • Identify challenges facing the commercialization of desiccant-enabled technologies. [ABSTRACT FROM AUTHOR]

To model urban airflow and dispersion near buildings and in street canyons, several Gaussian diffusion models, and diagnostic urban models and methods based on computational fluid dynamics (CFD), are developed to provide a fast and adequate response when hazardous material is released. The ESTE CBRN software tool computes the urban atmospheric variables using the Reynolds-averaged Navier–Stokes equations with the k–ε closure model. The dispersion is modelled by an Eulerian model linked to the calculated flow field. The ESTE CBRN results are compared with the Joint Urban 2003 Street Canyon Experiment for the instantaneous puff releases conducted within the Urban Dispersion International Evaluation Exercise project. Urban airflow is simulated with a steady-state approach where the time-averaged velocity is evaluated from local measurements conducted outside downtown Oklahoma City, USA. Twenty anemometer measurements inside the downtown area are used to verify the CFD calculation, after which 22 individual puff releases are considered. The modelled velocity and sampler responses are in moderate agreement with the measurements. Many compared variables, such as the mean wind speed and puff arrival time, are generally well reproduced, and fulfil the urban modelling criteria. The turbulent kinetic energy is, in general, underestimated by 30–40%. The modelled time series of sampler responses fulfil many, but not all, of the urban criteria, mainly due to differences in puff trajectories and a lower dispersion intensity. Additionally, the impact of applying various three-dimensional meshes on the predicted sampler responses is tested. [ABSTRACT FROM AUTHOR]

The article explores the shock-layer ionization in the Radio-Wave Attenuation Measurement for Study of Communication Blackout (RAM-C) program in the U.S. It mentions the two-dimensional problem of laminar air flow around a spherically blunted cone. It also notes the variation of the vibration energy at the expense of the occurrence of a chemical reaction.

One of the main economic activities in México is horticulture production in protected environments for the US market. The area under protected agriculture increases about 20 % yearly, notwistanding production is restricted by high and low temperatures during specific periods. This poses the need for a cooling system. Efficient natural ventilation is an effective method for controlling climate, but its description is complex and requires more knowledge of the process. The objective of this study was to visually represent the air flow and temperature distribution in a cenital greenhouse with 10 spans (110×90×4.7), typical in central Mexico, by posing and solving the physical model of air movement. A totally developed (LAI=4) tomato (Lycopersicon esculentum Mill.) crop was simulated. The model uses the computational fluid dynamics (CFD) approach and was structured and validated in the installations of the Institut de Recerca i Technolgía Agroalimentaries (IRTA) de Cabrils, Barcelona, Spain, from 2009 to 2010. Analysis of the results indicates significant differences in air flow due to the direction of window opening. The 3-Dimensional numerical analysis (CFD) enabled overall visualization of the spatial distribution of the climate inside the greenhouse and its climatic deficiencies. For wind speeds of 3 m s-1 in the first five spans, lateral ventilation is more important than roof ventilation because of wind or thermal effects. The combination of lateral and roof window opening increases thermal uniformity in the greenhouse by 30 % due to greater exchange flow through the roof windows, contributing fresh air to the interior, which maintains maximum gradients of 5-8 K. [ABSTRACT FROM AUTHOR]

Monthly precipitation datasets collected at 160 stations in China as well as the monthly winds and humidity data derived from the US National Centers for Environmental Prediction (NCEP) were used to construct the relationship between six summer dry-wet modes in eastern China and the summer monsoon airflow northward advance in East Asia. A millennial series of the monsoon dry-wet index (MDWI) was reconstructed based on Wang's six summer dry-wet modes in eastern China since 950 AD. A high (low) index indicates that the strong (weak) East Asian summer monsoon airflow can reach northern (southern) China and cause above (below) normal precipitation. Interdecadal periodic variations, such as the approximate 70-year oscillation, can be found in the MDWI series. In the last millennium, northern China has experienced persistent decadal wet periods and persistent decadal dry periods. At present, the MDWI is a low period on the interdecadal time scale so above-normal precipitation is observed in southern China and below-normal precipitation in northern China. [ABSTRACT FROM AUTHOR]

In this work, high-order computations of the flowfield around a 1303 unmanned combat air vehicle configuration are performed and compared with recently collected experimental data obtained at Lehigh University. The computational approach used a high-order overset-grid flow solver developed in the Air Vehicles Directorate of the U.S. Air Force Research Laboratory that employs up-to-sixth-order compact finite differences and high-order, low-pass numerical filters to accurately resolve detailed flow features in a robust manner. The experimental data was collected via a particle image velocimetry technique in a free-surface water channel. Both quantitative and qualitative comparisons between computational and experimental results are done at a plane located at eight-tenths of the half-span for various Reynolds numbers and angles of attack, with the results comparing quite favorably for most flow conditions. Computational images of the flowfield are used to elucidate angle of attack and Reynolds number effects on this configuration, as well as to investigate the formation and evolution of the leading-edge and centerbody vortical structures and the impact that angle of attack has on their formation mechanisms. [ABSTRACT FROM AUTHOR]

In previous studies, an air-blocking shelf has been shown to be successful in reducing respirable dust leakage from the drill shroud in a laboratory setting. Dust reductions of up to 81% were achieved with the shelf under operating conditions consisting of a 1.9:1 collector-to-bailing airflow ratio and a 5.1-cm gap between the shroud and ground. Recent research focused on evaluating the shelf on two actual operating blasthole drills, in much more severe environments. In the field, the shelf reduced dust levels in the areas surrounding one operating blasthole drill by 70%. Dust reductions measured in the immediate vicinity of the shroud were reduced by 66% at one mine and 81% at the other mine. These field tests confirm that the air-blocking shelf is useful for reducing respirable dust generation from blasthole drills. [ABSTRACT FROM AUTHOR]

Aerosol filter face velocities can be underestimated when the sample deposit area does not cover the entire face of the filter. In many aerosol samplers, Teflon filters are backed with a metal support screen. In these samplers, air flows through the filter only in the small area upstream of each hole in the screen, resulting in a sample deposit that is an array of tiny dots that mimics the array of holes. Thus, the filter deposit area is smaller than the total filter area and the effective face velocity is greater than that calculated from the sample deposit envelope. The Interagency Monitoring of Protected Visual Environments (IMPROVE) network has used filter holders with two different screen hole arrays. The U.S. Environmental Protection Agency's Chemical Speciation Network (CSN) and the Federal Reference Method samplers also use a metal support screen, but with much smaller screen holes than IMPROVE. These networks also use larger filters and lower flow rates than those used in IMPROVE. Filter face velocities for all of these networks that are calculated using the actual deposit array area range from 1.6 to 3.5 times larger than those calculated incorrectly using the entire sample deposit envelope. [ABSTRACT FROM AUTHOR]

Under the sponsorship of the U.S. Department of Energy and U.S. Department of Homeland Security, a computational fluid dynamics (CFD) model for simulating airflow and dispersion of chemical/biological agents released in urban areas has recently been developed. This model, the Finite Element Model in 3-Dimensions and Massively Parallelized (FEM3MP), is based on solving the three-dimensional, time-dependent Navier–Stokes equations with appropriate physics submodels on massively parallel computer platforms. It employs finite-element discretization for effective treatment of complex geometries and a semi-implicit projection scheme for efficient time integration. A simplified CFD approach, using both explicitly resolved and virtual buildings, was implemented to improve further the model’s efficiency. Results from our model are continuously being verified against measured data from wind-tunnel and field studies. Herein, this model is further evaluated using observed data from intensive operation periods (IOP) 3 and 9 of the Joint Urban 2003 field study conducted in Oklahoma City, Oklahoma, in July 2003. The model simulations of wind and concentration fields in the near and intermediate regions, as well as profiles of wind speed, wind direction, friction velocity, and turbulent kinetic energy (TKE) in the urban wake region, are generally consistent with and compared reasonably well to field observations. In addition, this model was able to reproduce the observed split plume of IOP 3 and the end vortices along Park Avenue in IOP 9. The dispersion results and TKE profiles at the crane station indicate that the effects of convective mixing are relatively important for the daytime release of IOP 3 but that the stable effects are relatively unimportant for the nighttime release of IOP 9. Results of this study also suggest that the simplified CFD approach implemented in FEM3MP can be a cost-effective tool for simulating urban dispersion problems. [ABSTRACT FROM AUTHOR]

Wind and tracer data from the Oklahoma City Joint Urban 2003 (JU2003) and the Manhattan Madison Square Garden 2005 (MSG05) urban field experiments are being analyzed to aid in understanding air flow and dispersion near street-level in built-up downtown areas. The mean winds are separately calculated for groups of anemometers having similar exposures such as “near street level” and “on building top”. Several general results are found, such as the scalar wind speed at street level is about 1/3 of that at building top. Turbulent standard deviations of wind speed components and temperature, and vertical fluxes of momentum and sensible heat, are calculated from sonic anemometers near street level at 20 locations in JU2003 and five locations in MSG05, and from two rooftop locations in MSG05. The turbulence observations are consistent with observations in the literature at other cities, although the JU2003 and MSG05 data are unique in that many data are available near street level. For example, it is found that the local (i.e., at the measuring height) $$\sigma_{w}/u_{\ast}$$ averages about 1.5 and the local $$u_{\ast}/u$$ averages about 0.25 in the two cities, where $$\sigma_{w}$$ is the standard deviation of vertical velocity fluctuations, $$u_{\ast}$$ is the friction velocity, and u is the wind speed. The ratio of temperature fluctuations to temperature scale, $$\sigma_{T}/T_{\ast}$$ , averages about −3 in both cities, consistent with similarity theory for slightly unstable conditions, where $$\sigma_{T}$$ is the standard deviation of temperature fluctuations, and $$T_{\ast}$$ is the temperature scale. The calculated Obukhov length, L, is also consistent with slightly unstable conditions near street level, even at night during JU2003. The SF6 tracer concentration observations from JU2003 are analyzed. Values of $$uC_{max}/Q$$ for the continuous releases are calculated for each release and arc distance, where $$C_{max}$$ is the 30-min average arc maximum concentration, Q is the continuous source emission rate, and u is the spatial-averaged wind speed in the downtown area. The basic characteristics of the JU2003 plot of averaged $$uC_{max}/Q$$ agree reasonably well with similar plots for other urban experiments in Salt Lake City and London (i.e., at $$x < 1000 m, C_{max}/Q = Ax^{-2})$$ . A is found to be about 3 during the day and about 10 during the night. [ABSTRACT FROM AUTHOR]

A new continuous flow diffusion chamber (CFDC) has been designed and constructed to study the ice nucleation efficiency of natural and anthropogenic aerosol particles over a range of temperatures and supersaturations. The CFDC system at Dalhousie University, Canada is based on the design of (Rogers et al. 1988, 1994) at Colorado State University, USA. A steady airflow (2.83 lpm) composed of sheath flows and an aerosol flow passes through the annular gap of the diffusion chamber. The walls of the chamber are ice-covered and are held at different temperatures. Aerosol particles are injected into the center of the gap near the location of maximum supersaturation. Particles greater than 5 µm in aerodynamic diameter are removed with impactors before entry to the chamber. Ice crystals are identified with an optical particle counter at the outlet of the chamber. In this article we report on the ice nucleation results of two mineral dust particles of potential atmospheric relevance, kaolinite and montmorillonite. Our results indicate that kaolinite and montmorillonite act as efficient ice nuclei in deposition/condensation nucleation mode. The onset relative humidity of both kaolinite and montmorillonite mineral dust particles were determined. The percentage of active ice nuclei is higher in montmorillonite compared to kaolinite at each temperature within the experimental conditions. The fraction of active ice nuclei increases with decreasing temperature and also with increasing relative humidity. [ABSTRACT FROM AUTHOR]

From measurements of surface heat transfer on the roofs of two commercial buildings in Northern California we have developed a correlation that expresses the outside convective air-film coefficient for flat, horizontal roofs as a function of surface-to-air temperature difference, wind speed, wind direction, roof size, and surface roughness. When used in detailed building energy analysis programs, this correlation is expected to give more accurate calculation of roof loads, which are sensitive to outside surface convection. In our analysis, about 90% of the variance of the data was explained by a model that combined standard flat-plate equations for natural and forced convection and that took surface roughness into account. We give expressions for the convective air-film coefficient: (1) at an arbitrary point on a convex-shaped roof, for a given wind direction; (2) averaged over a strip along the wind direction; and (3) averaged over a rectangular roof for a given wind direction. [Copyright &y& Elsevier]

Describes a numerical inverse method used to interpret simultaneously multirate injection and recovery data from single-hole pneumatic tests in unsaturated fractured tuff. Single-hole pneumatic tests at the Apache Leap Research Site in Arizona; Conceptual model of airflow during pneumatic tests at the site; Analysis of the single-hole and cross-hole pneumatic tests.

Studies the evolution of island airflow, thermodynamic fields and clouds over the island of Hawaii at night. Description of the model employed; Analysis of the cloud distribution during the nocturnal hours; Effects of the rain evaporative cooling on the katabatic flow.

Part I. Studies the airflow and cloud distributions over the island of Hawaii. Features of the island airflow and cloud distributions; Description of the model employed; Effects of trade wind inversion.

Investigates the interaction between the nighttime downslope-offshore flow and trade-wind rainshowers on the island of Hawaii in August 7-8, 1990. Analysis of the transition between the upslope-onshore and downslope-offshore flows under trade-wind conditions; Effect of rainfall on the evolution of downslope flow; Enhancement of trade-wind rainshowers by the downslope flow under trade-wind conditions.

Deformations of Engelmann spruce and subalpine fir trees were surveyed for the purpose of determining climatic wind speeds and directions and snow depths in the Glacier Lakes Ecosystem Experiments Site (GLEES) in the Snowy Range of southeastern Wyoming, USA. Tree deformations were recorded at 50- and 100-m grid intervals over areas of c. 30 ha and 300 ha, respectively, over the GLEES. The climatic mean wind speed was estimated to be 7-4m s-1; the mean air flow was predominantly westerly. The snow depths ranged from less than 0.2m to 5.5m. depending on topographic features and vegetative architecture. Compared with snow depth surveys, precipitation measurements, and a degree-day snow depth model, the average snow depth estimated by the tree deformation method was 70% of the long-term mean. The tree deformation method was useful for detailed estimates of wind speed, wind direction, and snow depth at a fine scale in complex terrain where meteorological instrumentation and snow survey data are minimal. [ABSTRACT FROM AUTHOR]

An abrupt ecotone in the vicinity of Valparaiso, Indiana, which separates forest communities consisting principally of beech and sugar maple from those dominated by black oak and white oak, coincides with the western margin of the LaPorte, Indiana precipitation anomaly. This ecotone is spatially related to a subsoil texture gradient. but its relationship to the precipitation pattern is doubtful. Tree-ring variation in living tree near LaPorte reveals patterns of cross-dating and climatic correlation which might be expected if the described precipitation pattern is real. Subsident mesoseale air flows (the lake breeze) from Lake Michigan in summer might contribute to occasional unexpected rainfall in northwestern Indiana. [ABSTRACT FROM AUTHOR]

The article describes the weather in Canada in November 2005. Air flow from the Pacific Ocean and the southern U.S. contributed to higher than normal temperatures. A tornado devastated Hamilton, Ontario on the 8th, causing power failures, uprooted trees, the partial collapse of an industrial building and other structural damage. Winter storms affected Manitoba, Ontario and Quebec around mid-November.