Long-term trends in ambient fine particulate matter from 1980 to 2016 in United Arab Emirates

© 2019, Springer Nature Switzerland AG. This paper presents the most comprehensive datasets of ambient fine particulate matter (PM 2.5 ) for the UAE from 1980 to 2016. The long-term distributions of PM 2.5 showed the annual average PM 2.5 concentrations constantly exceeded the EPA and WHO guidelines. They varied from 77 to 49 μg/m 3 with an overall average of 61.25 μg/m 3 . While the inter-annual variability in PM 2.5 concentrations showed relatively a cyclic pattern, with successive ups and downs, it broadly exhibited an increasing trend, particularly, over the last 14 years. PM 2.5 concentrations displayed a strong seasonal pattern, with greatest values observed during warm summer season, a period of high demand of electricity and dust events. The lowest values found in autumn are attributable to reduced demand of energy. Decreased atmospheric temperatures and high relative humidity coinciding with this period are likely to reduce the secondary formation of PM 2.5 . The spatial changes in PM 2.5 concentrations exhibited gradual downward trends to the north and northeast directions. Airborne PM 2.5 is prevalent in the southern and western regions, where the majority of oil and gas fields are located. PM 2.5 /PM 10 ratio indicated that ambient aerosols are principally associated with anthropogenic sources. Peaks in PM 2.5 /CO ratio were frequently observed during June, July, and August, although few were concurrent with March. This indicates that secondary formation plays an important role in PM 2.5 levels measured in these months, especially as the photochemical activities become relatively strong in these periods. The lowest PM 2.5 /CO ratios were found during September, October, and November (autumn) suggesting a considerable contribution of primary combustion emissions, especially vehicular emissions, to PM 2.5 concentration. PM 2.5 concentrations are positively correlated with sulfate levels. In addition to sea and dust aerosols, sulfate concentration in the coastal region is also related to fossil fuel burning from power plants, oil and gas fields, and oil industries. The population-weighted average of PM 2.5 in UAE was 63.9 μg/m 3 , which is more than three times greater than the global population-weighted mean of 20 μg/m 3

Seasonal impact to air qualities in industrial areas of the arabian gulf region

© 2018 Korean Society of Environmental Engineers. Air quality conditions and pollution status have been evaluated in the industrial area between Sharjah and Ajman border in UAE. Daily concentrations of O3, CO, NO2, SO2, PM2.5, PM10, Total Volatile Organic Compounds (TVOC) and Total Suspended Particulate (TSP) have been monitored from Sept. 2015 to April 2016. The monthly average concentrations of O3, CO, NO2, SO2, TVOC were within the UAE ambient air quality standards during the survey period. However, PM10 and TSP levels exceeded the recommended limits in Sept. 2015, Oct. 2015 and March 2016. Temporal variations in air quality parameters showed highest levels in March 2016 for PM2.5, PM10, NO2, TVOC and TSP, whereas O3, SO2 and CO showed relatively low values in this month. PM2.5 levels in ambient air were above the EPA guideline of 35 μg/m³ in all months. PM2.5 was the critical ambient air pollutant with Index for Pollutant (Ip) values varying from 103-209, indicating Air Quality Index categories of unhealthy for sensitive groups (62.5%) to unhealthy (25%) to very unhealthy (12.5%). The Ip average values of PM2.5 decreased from Sept. 2015 to reach lowest value in Dec. 2015 before increasing gradually, peaking in March 2016. These results suggest the potential health risks associated with PM2.5 is low in winter, where the prevailing meteorological conditions of lower temperatures, higher humidity, higher wind speed reduced particulate matter. The results revealed the industrial area is impacted by anthropogenic and natural sources of particulate matter

Investigation of in-plane moment connections of I-beams to square concrete-filled steel tube columns under gravity loads

AbstractThis paper focuses on experimental and analytical behavior of the ultimate moment of the connections of steel I-beams to square concrete-filled steel tube columns. External stiffeners around the columns are used at the beam flange levels. Five specimens are tested monotonically. The test parameters are the column stiffener dimensions and filling the steel tube column with concrete. Two types of failure modes are observed; beam flange failure and stiffener failure. The experimental results show that the ultimate moment of the connection is increased by increasing stiffener’s dimensions and filling the steel tube column with concrete. ANSYS finite element program is used to simulate the behavior, taking into account both geometric and material nonlinearities. Analytical results that are in fair agreement with the experimental ones are then used to discuss the influence of the main geometric parameters on the connection behavior. The parameters are the stiffener and column dimensions as well as filling the steel tube column with concrete. Different square column cross sections are chosen to cover the three classes of section classifications according to Egyptian code of practice, which are: compact, non compact or slender. The increase in the ultimate moment of the connections is based upon both column cross sections’ compactness and stiffener dimensions while the maximum advantages occur with slender columns

The Comparative Study of Biaxial Bending Analysis of Steel Sections Using AISC and Eurocode Approaches

ABSTRACT This study investigates the capacity of the steel section using both AISC and Eurocode approaches by Robot Structure Analysis software. Three types of steel sections were subject to biaxial bending by applying loads to both main axes and examined by both approaches. The concept of Fisher was also adopted as an approach. The findings suggested that the Eurocode approach is more conservative in the design of steel sections subject to biaxial bending as it takes into account the level at which the load is applied, the type of the section whether rolled or welded and its height-to-width ratio (lateral buckling effect), the effects which are not considered in AISC approach. The AISC approach considers the shear center of the section as the level at which the loads are applied. The conservatism of the results was more pronounced when the section is close to H-section. Fisher`s concept of structural design of biaxial bending of structural steel is more conservative than both AISC and Eurocode approaches of analysis

Nonlinear Channel Estimation Error Effect on Capacity of MIMO System

This paper presents the effect of nonlinearity and the effect of estimation error on the channel capacity in MIMO system. We consider a nonlinear MIMO channel, and compare the capacity of Rayleigh MIMO channel model with estimation error with the nonlinear model, at different estimation errors. We consider the estimation error as Gaussian distribution. The simulation results show that the channel capacity of linear and nonlinear MIMO channels are sensitive to the channel estimation error, and due to the nonlinearity, the capacity is less than linear channel. Keywords: MIMO, MIMO Modeling, channel capacity, channel estimation error, nonlinear MIMO channel.

Assessment of heavy metals in roadside dust along the Abu Dhabi–Al Ain National Highway, UAE

© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Concentrations of key heavy metals (Pb, Zn, Cd, Ni, Cr, Mn, As, and Hg) have been investigated in roadside dust collected from Abu Dhabi–Al Ain National Highway in UAE. The heavy metals contents were analyzed by atomic absorption spectrometer. Heavy metal levels varied widely from 227.9 to 2765, 19 to 1540, 37.4 to 398.6, 20.1 to 123, 0.3 to 0.7, 0.1 to 0.9, 0.1 to 0.7, and 0.1 to 0.5 mg/kg for Mn, Cr, Zn, Pb, Cd, Hg, Ni, and As, respectively. The spatial distribution pattern showed that different sources of roadway metal emissions dominate at specific locations. Peaks in heavy metal concentrations were frequently observed in locations with high traffic volume, road intersections and junctions, gas and bus stations. Decreased levels of heavy metals were measured in locations with low traffic loadings and in close proximity to farm and forest areas. In addition to traffic-related heavy metals, emissions from fossil fuel and industries remain of significance. Natural sources, through regular dust storms, are important contributors to the observed metal levels. Enrichment factor indicated that As and Ni were entirely originated from crustal sources. Cd, Zn, Pb, and Mn were moderately enriched and are probably derived from mixed sources (traffic flows, gas stations, construction and agricultural activities, among others). Road dust was significantly enriched in Cr and Hg indicating their dominant anthropogenic origin. The average geo-accumulation index values suggested that road dust are uncontaminated with Mn, Ni, and As, uncontaminated to moderately contaminated with Zn and Pb, and moderately contaminated with Cr, Cd, and Hg. The contamination factors indicated very highly contaminated road dust with Cr and Hg, considerably contaminated with Cd, and moderately contaminated with Mn, Zn, and Pb. Results of ecological risk assessment revealed that all heavy metals in road dust pose low risk to local ecosystems, except for Cd and Hg, which constitute potentially considerable risk and high risk, respectively

Baseline marine investigation and impact of fish farming on the marine environment in Jebel Ali, Dubai, United Arab Emirates

© 2020 Scattered seashells were observed on the seabed with no marine corals. The baseline studies indicate that biodiversity decreased from the northeast to southwest direction. The dominant groups of phytoplankton were diatoms followed by dinoflagellates, with insignificant vertical variations in species composition and population due to shallow water. The benthic diversity over the majority of the study area was relatively low compared with other nearshore areas in the region. All subtidal habitats showed evidence of disturbance to varying degrees, with no fish species recorded at these locations. The soft sediment habitat was found to cover much of the area footprint, and faunal diversity was very low. Fish diversity and abundance were equally poor with only a few demersal species recorded. No evidence of coral colonization was recorded although the presence of a low-profile, encrusting species was recorded in close proximity, to the east of the study area. Mangrove, coral, and seagrass were absent in the study area and its immediate vicinity. Modelling of waste plume suggested that the harbor water is fairly well-mixed, and the dispersion of ammonia attenuates with distance

Evolution of Patient Dose in Chest Radiotherapy Planning

Radiographic image has been used for patient positioning, target localization radiation beam alignment, and subsequent verification of treatment delivery in radiotherapy. Radiographic imaging as all medical use of ionizing radiation can give significant exposure to the patient. The aim of this study was to determine the radiological dose for chest imaging. Imaging dose during course of radiotherapy add dose to high therapeutic dose therefore this raises the issue of the balance between the benefit of these additional imaging exposures and the associated risk of radiation induced cancer arising from them. Therefore, estimation of imaging doses and possibility of its risk is necessary to provide adequate justification of this exposure. In this dissertation the main investigated type of the X-ray simulation were chest AP and PA, the total number of patients was 10 ( 62 radiographs). The fluctuation of the entrance surface dose (ESD) was relatively ranging from 0.35 micro;Gy to 8.43 micro;Gy for AP projection, and from 0.12 micro;Gy to 0.46 micro;Gy for PA projection. The mean values of ESD were found to be within guidance limits which was proposed in some countries (CEC 2004, and Germany 2003)