Search Results (13)

With the startup of the aero-engine, the ground vortex is formed between the ground and the engine intake. The ground vortex leads to total pressure and swirl distortion, which reduces the performance of the engine. The inhalation of the dust and debris through a ground vortex can erode the fan blade, block the seals and degrade turbine cooling performance. As the diameter of the modern fan blade becomes larger, the clearance between the intake lip and the ground surface is smaller, which enhances the strength of the ground vortex. Though considerable numerical studies have been conducted with the predictions of the ground vortex, it is noted that the accurate simulation of the ground vortex is still a tough task. This paper presents authors’ simulation work of the ground vortex into an intake model with different crosswind speeds. This paper tackles the challenge with a parametric study to provide useful guidelines on how to obtain a good match with the experimental data. The influence of the mesh density, performance of different turbulence models and how the boundary layer thickness affects the prediction results are conducted and analysed. The detailed structure of the flow field with ground vortex is presented, which can shed light on the experimental observations. A number of suggestions are presented that can pave the road to the accurate flow field simulations with strong vorticities. Full article

Characterizing the influence factors of exhaust gas based on the suspended road dust on paved roads, according to the number of vehicles and their distance with regard to driving pattern, is important in order to provide a coefficient for driving patterns to find a model equation. This has been a limitation of previous studies, in which this was difficult to carry out in a large area reflecting various driving patterns because some sections were selected according to empirical measurement results, and only one vehicle measurement was used to find the level of road dust. This study measured the concentration of suspended road dust that could occur, depending on the vehicle’s driving patterns, on an experimental road in Yongin, South Korea, from May to July 2023. The study was conducted to determine the degree of the effect of exhaust gas, according to the concentration of suspended road dust generated, by determining the separation distance based on real-time measurements. This study attempted to determine the changes in suspended road dust based on driving patterns in urban areas and factor in the concentration of suspended road dust with regard to emission characteristics in terms of exhaust gas and particulate matter with a diameter of 10 microns or less (PM₁₀). This was in accordance with conditions evaluated using mobile laboratories, based on suspended-PM₁₀-concentration-measuring equipment. This study mainly focused on the following main topics: (1) increasing the level of suspended particulate matter at less than 10 m intervals produced by exhaust gas; (2) decreasing the level of suspended road dust with an increase in the number of vehicles, with the area measured at a distance of three cars in front showing the lowest level of suspended road dust in the air and a low level for the rear vehicle; (3) demonstrating that PM₁₀ is effective in measuring the generation of suspended road dust; and (4) evaluating suspended road dust levels by road section. Based on the results, this research is necessary to more appropriately set the focus of analyses that aim to characterize suspended road dust according to exhaust gas and PM₁₀ content in silt. Full article

India is confronted with the substantial issue of plastic debris due to the absence of an efficient waste management infrastructure. Recycled plastic has the potential to enhance various construction materials, such as roofing tiles, paving blocks, and insulation. The aforementioned materials possess notable attributes such as high strength, low weight, and exceptional resistance to extreme temperatures and humidity. The objective of this study is to ascertain feasible alternatives for manufacturing road paver blocks utilizing plastic waste (Polyethene terephthalate (PET)), and M-sand (stone dust). Three variations of a discarded plastic cube measuring 150 mm × 150 mm × 150 mm were prepared for the experiment. The experimental findings indicated that a ratio of 1:4 was determined to be the most effective in achieving the desired level of compressive strength. I-section road and brick paver blocks were produced as an alternative to the traditional concrete ones. Compressive strength tests were performed on I-sections and brick paver blocks, revealing that the 1:4 mix ratio exhibited the highest average compressive strength for both materials. The findings indicated that including plastic waste positively impacted the compressive strength of the I-sections and brick paver blocks. Additionally, the quality grading of these materials was evaluated using an ultrasonic pulse velocity test. The ultrasonic pulse velocity test results demonstrated a high-quality grading for the I-sections and brick paver blocks. Scanning electron microscopy (SEM) tests assessed the microstructural behavior and performance. The results of this study demonstrate that incorporating plastic waste in combination with M-sand can effectively improve the mechanical characteristics of composite materials, rendering them viable for use in construction-related purposes. Full article

Medical waste incineration fly ash (MWIFA) contains heavy metals that are toxic by nature and pose numerous health risks. The paper deals with the suitability of MWIFA as a mineral filler in the bituminous layer as an alternative to conventional stone dust (SD) through an appropriate combination of engineering and environmental assessments. Engineering parameters, such as Marshall stability, stability loss, flow, unit weight, air voids (V_a), voids filled with asphalt (VFA), and voids in the mineral aggregate (VMA) of the asphalt mixtures, were evaluated with varying filler ratios, from 2% to 10%. All parameters for both fillers at optimum bitumen content satisfied the Marshall Mix Design criteria. The optimum bitumen contents of all filler ratios were within the standard limit recommended by the Bangladesh Roads and Highways Department. It was found that mixes prepared with MWIFA can resist moisture effects, making them durable in the monsoon. The mixes with 5.5% MWIFA as mineral filler performed the best, whereas 9% SD filler was required to achieve similar performance. The environmental test results show no environmental restriction on stabilizing the MWIFA into paving mixtures. The mobility of heavy metals (As, Pb, Cu, Cr, Ni, Cd, Hg, and Zn) from the asphalt-MWIFA mix was insignificant. The cumulative concentrations of heavy metals (Cd, Ni, Zn, Cu, and Pb) from long-term leaching tests were far below the Dutch regulatory limit (U1). MWIFA can be considered an eco-friendly and sustainable mineral filler for the dense bituminous pavement layer. Full article

Characterizing the influencing factors of resuspended dust on paved roads according to the atmospheric environment and traffic conditions is important to provide a basis for road atmospheric pollution control measures suitable for various road environments in the future. This study attempts to identify factors in the concentration of resuspended dust according to the level of road dust loading and PM₁₀ emission characteristics according to atmospheric weather environment and traffic conditions using real-time vehicle-based resuspended PM₁₀ concentration measuring equipment. This study mainly focuses on the following main topics: (1) the increased level of resuspended dust according to vehicle speed and silt loading (sL) level; (2) difference between atmospheric pollution at adjacent monitoring station concentration and background concentration levels on roads due to atmospheric weather changes; (3) the correlation between traffic and weather factors with resuspended dust levels; (4) the evaluation of resuspended dust levels by road section. Based on the results, the necessity of research to more appropriately set the focus of analysis in order to characterize the resuspended dust according to changes in the traffic and weather environment in urban areas is presented. Full article

Biogenic fraction of airborne PM₁₀ which includes bacteria, viruses, fungi and pollens, has been proposed as one of the potential causes of the PM₁₀ toxicity. The present study aimed to provide a comprehensive understanding of the microbial community variations associated to PM₁₀, and their main local sources in the surrounding environment in three urban sites of Rome, characterized by differential pollution rate: green area, residential area and polluted area close to the traffic roads. We combined high-throughput amplicon sequencing of the bacterial 16S rRNA gene and the fungal internal transcribed spacer (ITS) region, with detailed chemical analysis of particulate matter sampled from air, paved road surfaces and leaf surfaces of Quercus ilex. Our results demonstrated that bacterial and fungal airborne communities were characterized by the highest alpha-diversity and grouped separately from epiphytic and road dust communities. The reconstruction of source-sink relationships revealed that the resuspension/deposition of road dust from traffic might contribute to the maximum magnitude of microbial exchanges. The relative abundance of extremotolerant microbes was found to be enhanced in epiphytic communities and was associated to a progressively increase of pollution levels as well as opportunistic human pathogenicity in fungal communities. Full article

The SCAMPER mobile system for measuring PM₁₀ emission rates from paved roads was used to characterize emission rates from a wide variety of roads in the Phoenix, AZ metropolitan area. Week-long sampling episodes were conducted in March, June, September, and December. A 180 km-long route was utilized and traveled a total of 18 times. PM₁₀ emission rate measurements were made at 5-s resolution for over 3200 km of roads with a precision of approximately 25%. The PM₁₀ emission rates varied by over two orders of magnitude and were generally low unless the road was impacted with dust deposited by activities such as construction, sand and gravel operations, agriculture, and vehicles traveling on or near unpaved shoulders and roads. The data were tabulated into averages for each of 67 segments that the route was divided into. The segment-averaged PM₁₀ emission rates ranged from zero to 2 mg m⁻¹, with an average of 0.079 mg m⁻¹. There was no significant difference in emission rates between seasons. There was a major drop in emission rates over a weekend, when dust generation activities such as construction are expected to be much reduced. By Monday, the PM₁₀ emission rates had risen to the levels of the previous Friday. This indicates that roads quickly reach an equilibrium PM₁₀ generating potential. Full article

Road dust is one of the primary sources of particulate matter which has implications for air quality, climate and health. With the aim of characterizing the emissions, in this study, a bottom-up approach of county level emission inventory from paved road dust based on field investigation was developed. An inventory of high-resolution paved road dust (PRD) emissions by monthly and spatial allocation at 1 km × 1 km resolution in Harbin in 2016 was compiled using accessible county level, seasonal data and local parameters based on field investigation to increase temporal-spatial resolution. The results demonstrated the total PRD emissions of TSP, PM₁₀, and PM_2.5 in Harbin were 270,207 t, 54,597 t, 14,059 t, respectively. The temporal variation trends of pollutant emissions from PRD was consistent with the characteristics of precipitation, with lower emissions in winter and summer, and higher emissions in spring and autumn. The spatial allocation of emissions has a strong association with Harbin’s road network, mainly concentrating in the central urban area compared to the surrounding counties. Through scenario analysis, positive control measures were essential and effective for PRD pollution. The inventory developed in this study reflected the level of fugitive dust on paved road in Harbin, and it could reduce particulate matter pollution with the development of mitigation strategies and could comply with air quality modelling requirements, especially in the frigid region of northeastern China. Full article

As a closed space, the functional requirements of the tunnel pavement are very different from ordinary pavements. In recent years, with the increase of requirements for tunnel pavement safety, comfort and environmental friendliness, asphalt pavement has become more and more widely used in long tunnels, due to its low noise, low dust, easy maintenance, and good comfort. However, conventional tunnel asphalt pavements cause significant safety and environmental concerns. The innovative polyurethane thin overlay (PTO) has been developed for the maintenance of existing roads and constructing new roads. Based on the previous study, the concept of PTO may be a feasible and effective way to enrich the innovative functions of tunnel pavement. In this paper, the research aims to evaluate the functional properties of PTO, such as noise reduction, solar reflection and especially combustion properties. Conventional asphalt (Open-graded Friction Course (OGFC) and Stone Mastic Asphalt (SMA)) and concrete pavement materials were used as control materials. Compared with conventional tunnel pavement materials, significant improvements were observed in functional properties and environmental performance. Therefore, this innovative wearing layer can potentially provide pavements with new eco-friendly functions. This study provides a comprehensive analysis of these environmentally friendly materials, paving the way for the possible application in tunnels, as well as some other fields, such as race tracks in stadiums. Full article

Ninety-six particulate matter (PM₁₀) chemical source profiles for geological sources in typical cities of southwest China were acquired from Source Profile Shared Service in China. Twenty-six elements (Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Cd, Sn, Sb, Ba, Be, Tl and Pb), nine ions (F⁻, Cl⁻, SO₄²⁻, NO₃⁻, Na⁺, NH₄⁺, K⁺, Mg²⁺ and Ca²⁺), and carbon-containing species (organic carbon and elemental carbon) were determined to construct these profiles. Individual source profiles were averaged and compared to quantify similarities and differences in chemical abundances using the profile-compositing method. Overall, the major components of PM₁₀ in geological sources were crustal minerals and undefined fraction. Different chemical species could be used as tracers for various types of geological dust in the region that resulted from different anthropogenic influence. For example, elemental carbon, V and Zn could be used as tracers for urban paved road dust; Al, Si, K⁺ and NH₄⁺ for agricultural soil; Al and Si for natural soil; and SO₄²⁻ for urban resuspended dust. The enrichment factor analysis showed that Cu, Se, Sr and Ba were highly enriched by human activities in geological dust samples from south-west China. Elemental ratios were taken to highlight the features of geological dust from south-west China by comparing with northern urban fugitive dust, loess and desert samples. Low Si/Al and Fe/Al ratios can be used as markers to trace geological sources from southwestern China. High Pb/Al and Zn/Al ratios observed in urban areas demonstrated that urban geological dust was influenced seriously by non-crustal sources. Full article

Many studies have been performed in order to characterize the sources of airborne particles in the Metropolitan Area of São Paulo (MASP), in Brazil. Those studies have been based on receptor modeling and most of the uncertainties in their results are related to the emission profile of the resuspended road dust particles. In this study, we analyzed the composition of resuspended road dust particles in different environments: local streets, paved roads inside traffic tunnels, and high traffic streets. We analyzed the samples to quantify the concentrations of trace elements and black carbon. On the basis of that analysis, we developed emission profiles of the resuspended road dust that are representative of the different types of urban pavement in the MASP. This study is important given the international efforts in improving emissions factors with local characteristics, mainly in South America and other regions for which there is a lack of related information. This work presents emission profiles derived from resuspended road dust samples that are representative of the different types of urban pavement in the Metropolitan Area of São Paulo. Full article

Living near landfills is a known health hazard prompting recognition of environmental injustice. The study aim was to compare self-reported symptoms of ill health among residents of four neighborhoods, living in haphazardly constructed settlements surrounded by illegal dumpsites in Tijuana, Mexico. One adult from each of 388 households located in Los Laureles Canyon were interviewed about demographics, health status, and symptoms. Distance from each residence to both the nearest dumpsite and the canyon bottom was assessed. The neighborhoods were selected from locations within the canyon, and varied with respect to proximity to dump sites. Residents of San Bernardo reported significantly higher frequencies of ill-health symptoms than the other neighborhoods, including extreme fatigue (OR 3.01 (95% CI 1.6–5.5)), skin problems/irritations (OR 2.73 (95% CI 1.3–5.9)), stomach discomfort (OR 2.47 (1.3–4.8)), eye irritation/tears (OR 2.02 (1.2–3.6)), and confusion/difficulty concentrating (OR 2.39 (1.2–4.8)). Proximity to dumpsites did not explain these results, that varied only slightly when adjusted for distance to nearest dumpsite or distance to the canyon bottom. Because San Bernardo has no paved roads, we hypothesize that dust and the toxicants it carries is a possible explanation for this difference. Studies are needed to further document this association and sources of toxicants. Full article

Sustainable drainage systems (SuDS; or best management practices) are increasingly being used as ecological engineering techniques to prevent the contamination of receiving watercourses and groundwater. Permeable paving is a SuDS technique, which is commonplace in car parks, driveways and minor roads where one of their functions is to improve the quality of urban runoff. However, little is known about the water quality benefits of incorporating an upper geotextile within the paving structure. The review focuses on five different categories of pollutants: organic matter, nutrients, heavy metals, motor oils, suspended solids originating from street dust, and chloride. The paper critically assesses results from previous international tests and draws conclusions on the scientific rigour and significance of the data. Findings indicate that only very few studies have been undertaken to address the role of geotextiles directly. All indications are that the presence of a geotextile leads only to minor water quality improvements. For example, suspended solids are being held back by the geotextile and these solids sometimes contain organic matter, nutrients and heavy metals. However, most studies were inconclusive and data were often unsuitable for further statistical analysis. Further long-term research on industry-relevant, and statistically and scientifically sound, experimental set-ups is recommended. Full article