Dynamic Characteristics of Particle Size Distribution in Highway Runoff: Implications for Settling Tank Design

To understand the characteristics of particle size distribution (PSD) in highway runoff and to facilitate designing best management practices, PSD (2–1,000?μm) was monitored in seven rainfall events in the 2002–2003 rainy season at three highway sites in west Los Angeles. Most of the particles in number were less than 30?μm in diameter and more than 90% were less than 10?μm. Particle number concentration decreased rapidly to 6?mm of accumulated rainfall and then declined more slowly throughout the storm. Particle number concentration was correlated with total suspended solids (TSS) and turbidity. Grab sample particle median diameter increased with increasing TSS. A two-compartment settling tank was evaluated using the measured PSD and was effective in removing both small and large particles. Capturing and retaining the first 20% of the runoff volume on seasonal average can remove 40% of the total particulate load based on calculated particle mass. Using literature data for metal concentrations sorbed to particles, this size holding compartment coupled with a similar size continuous flow clarifier can achieve 65–90% removal for the metals investigated.     

Estimating Pollutant Mass Accumulation on Highways during Dry Periods

For determining the accumulated pollutant mass on highways, two years of monitoring data were used from eight highway sites in southern California. Buildup over antecedent dry days was calculated from mass washed off from the following storm and retained pollutant mass. Mass accumulation rates were determined for total suspended solids (TSS), chemical oxygen demand (COD), oil and grease, total Kjeldahl nitrogen, and total phosphorus, and are reported in g/m2-day. A revised buildup model is proposed using an alternative modeling approach to describe buildup during dry days between storms. The result shows that, between 1 and 10 antecedent dry days, the pollutant mass buildup rates are determined to be 0.544?g/m2-day for TSS, 0.114?g/m2-day for COD, and 0.0113?g/m2-day for oil and grease. Buildup rates decline in subsequent periods rates decreased by 79% for TSS, 78% for COD, and 61% less for oil and grease in the following 10–70?day period.     

Design of CO2 absorption plant for recovery of CO2 from flue gases of gas turbine

The ongoing human-induced emission of carbon dioxide (CO₂) threatens to change the earth's climate. A major factor in global warming is CO₂ emission from thermal power plants, which burn fossil fuels. One possible way of decreasing CO₂ emissions is to apply CO₂ removal, which involves recovering of CO₂ from energy conversion processes. This study is focused on recovery of CO₂ from gas turbine exhaust of Sarkhun gas refinery power station. The purpose of this study is to recover the CO₂ with minimum energy requirement. Many of CO₂ recovery processes from flue gases have been studied. Among all CO₂ recovery processes which were studied, absorption process was selected as the optimum one, due to low CO₂ concentration in flue gas. The design parameters considered in this regard, are: selection of suitable solvent, solvent concentration, solvent circulation rate, reboiler and condenser duty and number of stages in absorber and stripper columns. In the design of this unit, amine solvent such as, diethanolamine (DEA), diglycolamine (DGA), methyldiethanolamine (MDEA), and monoethanolamine (MEA) were considered and the effect of main parameters on the absorption and stripping columns is presented. Some results with simultaneous changing of the design variables have been obtained. The results show that DGA is the best solvent with minimum energy requirement for recovery of CO₂ from flue gases at atmospheric pressure.     

Implications of a kinematic wave model for first flush treatment design

A deterministic model was developed to predict pollutant mass first flush and to utilize it for better design of best management practices (BMPs) that focus on treating the first flush. The model used the kinematic wave equation to calculate flow and mass transport, and erosion equations to calculate pollutant concentrations, which were assumed to be from a short and a long term source. The model parameters were calibrated with a parameter estimation procedure using three years’ monitoring data from a highway runoff site in west Los Angeles. The simulation results showed that there exists an optimum watershed size to maximize first flush. Contours of watershed length, developed from simulations for different conditions of rainfall and watershed geometry, can be used to design runoff collection systems for highways and parking lots to maximize first flush.     

Performance of the sulfonated poly ether ether ketone proton exchange membrane modified with sulfonated polystyrene and phosphotungstic acid for microbial fuel cell applications

In this research, the preparation of low cost proton exchange membranes (PEMs) based on sulfonated poly ether ether ketone (SPEEK) for application in the microbial fuel cells (MFCs) is studied. Sulfonated polystyrene (SPS) and phosphotungstic acid (PWA) were employed to improve the performance of PEM through the creation of more proton pathways. At first, the sulfonation of PEEK and polystyrene were performed through two modified methods to obtain uniform and high degree of sulfonation (DS) of the polymers and then, the PEMs were prepared through the solution casting method. Accordingly, the formation of uniform skin layer was confirmed by the SEM micrographs. Blending the aforementioned additives to the SPEEK polymer solution significantly enhanced the proton conductivity, water uptake and durability of the modified membranes. The proton conductivities of SPEEK/SPS and SPEEK/PWA membranes at additive/SPEEK weight ratio of 0.15 were 45.3% and 26.2% higher than that of the commercial Nafion117 membrane, respectively. Moreover, the degradation times for the abovementioned modified membranes were 140 and 350 min which indicated satisfactory oxidation stability. Besides, the aforementioned membranes exhibited two times more water uptake compared to the neat SPEEK membrane. Finally, SPEEK/SPS and SPEEK/PWA membranes produced 68% and 36% higher maximum power in the MFC, compared to the commercial Nafion117 membrane. Therefore, the fabricated PEMs are potentially suitable alternatives to be used in the fuel cell applications.     

Mechanistic investigation of aluminide coating formation by low-pressure chemical vapor deposition method on NiCoCrAlY coating in presence of nickel-ceria composite layer

In this study, a hybrid coating comprised of NiCoCrAlY fabricated by HVOF method, Ni–CeO₂ composite coated by electrodeposition, and aluminide coating applied by low pressure chemical vapor deposition (LPCVD) method are investigated. To elucidate the formation process of aluminide coating, the microstructure and properties of the applied coatings were examined by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and EDS analyses. It was concluded that the desired β-NiAl phases are uniformly created within a single step on the surface. Furthermore, with the extending of the coating duration from 2 to 4 h, the thickness of the aluminide coating was increased from 14 to 25 μm. The thickness values were increased even further in the presence of Ni–CeO₂ coating, where the growth mechanism was also changed. Within 4 h, a coating with a thickness of roughly 50 μm was obtained. Moreover, in the presence of Ni–CeO₂ coating, it was observed that the inward diffusion of aluminum was predominant at the beginning of the process, whereas with longer processing durations, the outward diffusion of the nickel becomes dominant instead.     

Multi-criteria decision-making for controller placement in software-defined wide-area networks

The Journal of Supercomputing - Software-defined networks have many benefits such as more control over the control plane and reduced operating costs through separating the control plane from the...     

The improvement in obstacle detection in autonomous vehicles using YOLO non-maximum suppression fuzzy algorithm

The Journal of Supercomputing - Numerous changes in algorithms have been observed by object detection to enhance both speed and accuracy. In this research, we present a method to improve the...     

Effects of different filling media on the oxidation and lipid quality of canned silver carp (Hypophthalmichthys molitrix)

The influence of four different filling media (sunflower oil, soybean oil, olive oil and brine) on the oxidation and lipid quality of canned silver carp was evaluated. Hydrolytic rancidity showed that free fatty acid contents in brine and soybean oil canned muscle were higher than olive oil or sunflower oil canned samples. Conjugated diene (CD) levels in soybean oil canned samples increased but the highest CD values were found in canned silver carp using brine as filling medium. Except for olive oil canned muscle, significant increase in thiobarbituric acid (TBA) values was obtained. The highest TBA value was observed in soybean oil canned sample. Canning led to exchange of fatty acids between the fat in the silver carp muscle and the filling media used. Results indicate that the fat composition of canned silver carp tends to be similar to that of the fat used as filling media.