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Peyman Amir Nazmi Afshar Mehdy Gooya Seyed Vahid Hosseini 《International Journal of Green Energy》2017,14(11):868-877
The study deals with the design and optimization of external and internal geometry of micro-wind turbines blades. A specified objective function which consists of the power coefficient and the starting time was defined and the genetic algorithm optimization technique in conjunction with the blade-element momentum theory was adopted to find the geometry of the blades including the distributions of the chord, the twist angle and also the shell thickness. Moreover, the allowable stress of the blades was considered as a constraint to the objective function. Results show that a reasonable compromise is achievable such that the starting time of the blades reduces noticeably in return for a small drop in the power coefficient. The significant improvement of the hollow blades over the solid ones indicates that the power coefficient and the starting performance could be improved through the appropriate distributions of the considered decision variables, i.e. the chord, the twist angle and also the shell thickness. 相似文献
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Stock TH Morandi MT Afshar M Chung KC 《Journal of the Air & Waste Management Association (1995)》2008,58(10):1303-1310
The Houston-Galveston metropolitan area has a relatively high density of point and mobile sources of air toxics, and determining and understanding the relationship between emissions and ambient air concentrations of air toxics is important for evaluating potential impacts on public health and formulating effective regulatory policies to control this impact, both in this region and elsewhere. However, conventional ambient air monitoring approaches are limited with regard to expense, siting limitations, and representative sampling necessary for adequate exposure assessment. The overall goal of this multiphase study is to evaluate the use of simple passive air samplers to determine temporal and spatial variability of the ambient air concentrations of selected volatile organic compounds (VOCs) in urban areas. Phase 1 of this study, reported here, was a field evaluation of 3M organic vapor monitors (OVMs) involving limited comparisons with commonly used active sampling methods, an assessment of sampler precision, a determination of optimal sampling duration, and an investigation of the utility of a simple modification of the commercial sampler. The results indicated that a sampling duration of 72 hr exhibited generally low bias relative to automated continuous gas chromatography measurements, good overall precision, and an acceptable number of measurements above detection limits. The modified sampler showed good correlation with the commercial sampler, with higher sampling rates, although lower than expected. 相似文献
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Smith LA Stock TH Chung KC Mukerjee S Liao XL Stallings C Afshar M 《Environmental monitoring and assessment》2007,128(1-3):369-379
In the summer of 2003, ambient air concentrations of volatile organic compounds (VOCs) were measured at 12 sites within a
3-km radius in Deer Park, Texas near Houston. The purpose of the study was to assess local spatial influence of traffic and
other urban sources and was part of a larger investigation of VOC spatial and temporal heterogeneity influences in selected
areas of Houston. Seventy 2-h samples were collected using passive organic vapor monitors. Most measurements of 13 VOC species
were greater than the method detection limits. Samplers were located at 10 residential sites, a regulatory air monitoring
station, and a site located at the centroid of the census tract in which the regulatory station was located. For residential
sites, sampler placement locations (e. g., covered porch vs. house eaves) had no effect on concentration with the exception
of methyl tertiary-butyl ether (MTBE). Relatively high correlations (Pearson r > 0.8) were found between toluene, ethylbenzene, and o,m,p-xylenes suggesting petroleum-related influence. Chloroform was not correlated with these species or benzene (Pearson r < 0.35) suggesting a different source influence, possibly from process-related activities. As shown in other spatial studies,
wind direction relative to source location had an effect on VOC concentrations. 相似文献
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Farideh Abbaszadeh Afshar Ahmad Jalalian 《Journal of environmental radioactivity》2010,101(8):606-614
The spatial pattern of soil redistribution rate was investigated using cesium-137 (137Cs) within a cultivated complex hillslope in western Iran. The relationship between soil redistribution rate and soil organic carbon and total nitrogen pattern were studied using co-regionalization analysis. Ninety-one soil cores were sampled for 137Cs, total nitrogen, and soil organic carbon measurements. The simplified mass balance model estimated a gross erosion rate of 29.8 t ha−1 yr−1 and a net soil deposition rate of 21.8 t ha−1 yr−1; hence, a net soil loss rate of 8 t ha−1 yr−1. This magnitude of soil erosion rate is higher than the acceptable rate in semiarid regions. Co-regionalization analysis and co-dispersive coefficients among the selected variables showed that only a small fraction of the variability in total nitrogen and soil organic carbon could be explained by soil redistribution and that the remaining might be the result of different management practices by local farmers. 相似文献
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Afshar Abbas Soleimanian Elham Akbari Variani Hossein Vahabzadeh Masoud Molajou Amir 《Environment, Development and Sustainability》2022,24(8):10119-10140
Environment, Development and Sustainability - Several models with a variety of concepts and approaches have been proposed to address different aspects of the Water-Energy-Food (WEF) nexus system.... 相似文献
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