Starting improvement of micro-wind turbines operating in low wind speed regions

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.     

Biodegradation of styrene laden waste gas stream using a compost-based biofilter

Biological treatment of waste gas styrene vapor was investigated in a three-stage bench-scale biofilter. Yard waste compost mixed with shredded hard plastics in a 25:75 v/v ratio of plastics:compost was inoculated with thickened municipal activated sludge. Microbial acclimation to styrene was achieved by exposing the system to an inlet concentration (C(In)) of 0.25 gm(-3) styrene and an empty bed retention time (EBRT) of 360 s for 30 days. Under steady-state conditions, maximum elimination capacity (EC) obtained was 45 gm(-3)h(-1) at a loading rate (L) of 60 gm(-3)h(-1) (C(In) of 2 gm(-3) and EBRT of 120 s). Reduction of retention time adversely impacted the performance resulting in the maximum EC of 39 and 27 gm(-3)h(-1) for EBRT of 60 and 30 s, respectively. Evaluation of the concentration profile along the bed height indicated dominance of first-order kinetics at C(In) < or = 0.45 gm(-3) and zero-order for higher concentrations.     

Conceptual compression discussion on a multi-linear (FTA) and systematic (FRAM) method in an offshore operation’s accident modeling

Risk assessment can be classified into two broad categories: traditional and modern. This paper is aimed at contrasting the functional resonance analysis method (FRAM) as a modern approach with the fault tree analysis (FTA) as a traditional method, regarding assessing the risks of a complex system. Applied methodology by which the risk assessment is carried out, is presented in each approach. Also, FRAM network is executed with regard to nonlinear interaction of human and organizational levels to assess the safety of technological systems. The methodology is implemented for lifting structures deep offshore. The main finding of this paper is that the combined application of FTA and FRAM during risk assessment, could provide complementary perspectives and may contribute to a more comprehensive understanding of an incident. Finally, it is shown that coupling a FRAM network with a suitable quantitative method will result in a plausible outcome for a predefined accident scenario.     

Biological nutrient recovery from culturing of pearl gourami (Trichogaster leerii ) by cherry tomato (Solanum lycopersicum) in aquaponic system

Environmental Science and Pollution Research - The possibility of using different densities of cherry tomato as a bio-filter in a simple media-based aquaponic system to recycle nutrients from pearl...     

Government management and overexploitation of groundwater resources: absence of local community initiatives in Ardabil plain-Iran

Although mismanagement of groundwater resources has resulted in their destruction over centuries, climate change is speeding up this process more than ever. On the one hand, urgent action by government bodies is needed to address the challenge. On the other hand, a vast body of literature proves that bottom-up collective action, although requiring a longer time period, is a better solution to manage such resources. This research aims to address this dilemma. The groundwater resource in Ardabil plain in Iran, which has long been managed solely through government intervention, has been chosen as a case study to explore the opportunities and limitations of managing a critically endangered area from a common pool resource perspective. Our study suggests that managing Ardabil groundwater resources should be conducted on two scales. The bottom-up institutional agreements should take place at village scale while the government should stay in charge of the overall organization at plain scale.