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Volume 3 : Issue 6, November 2013
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Table of Content, 25 November 2013
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A Comparison of Bituminous Coal-Based and Coconut Shell-Based Activated Carbon for Removal of Trace Hazardous Air Pollutants in Landfill Gas
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Original Article, C49 ABSTRACT:This study explored adsorption as a method of controlling hazardous air pollutant emissions from landfill gas (LFG). In particular, the study compared bituminous coal-based (BPL) and coconut shell-based (OVC) activated carbons as adsorbents for the hazardous landfill gas constituents para-, ortho-, and meta-xylene; ethylbenzene; and methyl ethyl ketone (MEK). Experiments were designed to replicate typical field usage conditions, using ambient temperature and relative humidity values, and testing the carbon as is, without pretreatment to remove moisture. BPL and OVC carbons from Calgon Carbon were tested in vials, with initial headspace concentrations ranging from 2130 to 5020 ppmv (86 to 120 mg/m3). Pollutant concentration remaining in the headspace at equilibrium was measured using an SRI 8610 gas chromatograph with flame ionization detector. Tests were conducted at 45-70% relative humidity and room temperature. Adsorption curve fits of Langmuir and Freundlich isotherms (LI and FI) were determined for each compound and each type of activated carbon. For MEK, BPL and OVC adsorption capacities were similar for all concentrations. For ethylbenzene and the xylene isomers, however, OVC coconut shell-based carbon had a higher adsorption capacity at lower concentrations, but BPL coal-based carbon had a higher capacity at higher concentrations. This is likely due to the greater external surface area for OVC carbon, and the greater internal surface area for BPL carbon. For both carbons, at low concentrations adsorption capacity was highest for ethylbenzene, at intermediate concentrations highest for para-xylene, and at high concentrations highest for ortho-xylene. For ethylbenzene and MEK, the Freundlich isotherm fit the data better; for the xylenes, the Langmuir isotherm generally fit the data better. Manufacturer isotherms, developed for ideal conditions, predicted significantly higher maximum adsorption capacities than those determined in this research. Both bituminous coal-based and coconut shell-based activated carbons showed promise for removing hazardous air pollutants from landfill gas, for different concentration levels. |
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Removal of Cadmium from Soil Resources Using Stabilized Zero-Valent Iron Nanoparticles
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Original Article, C50 ABSTRACT:Studying the removal of environmental pollutants such as heavy metals is important from various aspects, particularly human health-related issues. The present study evaluated the effect of zero-valent iron nanoparticles on the removal of cadmium from soil resources. To this aim, zero-valent iron nanoparticles were made with carboxymethyl cellulose stabilizer. Based on the results of cadmium removal from contaminated soil by application of nanoparticles, the distribution of cadmium in different parts of the soil was as follows: carbonate > exchangeable > oxide > residual > dissolved. Generally, the results of this study suggest that zero-valent iron nanoparticles are suitable adsorbents for removal of cadmium. Moreover, using polymer coatings such as carboxymethyl cellulose leads to increment of sustainability and diffusion of nanoparticle suspensions which in turn increases the removal efficiency of bioenvironmental pollutants. |
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The Hydraulics of Flow in Non-Prismatic Compound Channels
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Original Article, C51 ABSTRACT:This paper investigates the effects of floodplains' roughness the on hydraulic overbank flow in compound channels with non-prismatic floodplains. Experiments are carried out using three divergence angles and three roughness sizes on the floodplain. The velocity was measured using a three dimensional acoustic Doppler velocimeter and directional current meter in a lattice along the divergence channel with different depth ratios. Velocity distributions on the half-width of the channels in three portion of the flume (entrance, middle and end of the divergence) were measured. Using the experimental data about the values of the shear stress, depth–averaged velocity, roughness coefficient, turbulence parameters and divided discharge between the main channel and floodplain, the water surface slope was evaluated. Also these results were compared with the prismatic compound channel and also compared using the Shiono-Knight method. |
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Floodplain Vegetation Contribution to Velocity Distribution in Compound Channels
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Original Article, C52 ABSTRACT:The flow in compound open-channel is characterized by a complex flow structure due to the interaction between the main channel and floodplain which is often home to a lot of kinds of vegetation. This paper describes the results of an experimental study on the influence of floodplain vegetation on velocity distribution in compound channels. For vegetation on the floodplain, rigid cylindrical rods 1 cm in diameter are used. The local flow velocities for different densities of vegetation were measured using a 3D acoustic Doppler velocimeter. The results showed that that after implanting the vegetation over the floodplain, the depth averaged velocity over the floodplain increases whereas it increases in the main channel. Also, the depth averaged velocity decreases in both the main channel and floodplain with an increase in the vegetation density. The maximum value of the streamwise velocity was found to decreases with vegetation density. While it was found that a major vortex forms in the main channel for smooth floodplain, two distinct vortexes (free surface and bottom vortexes) were observed for the tests with vegetated floodplain. |
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Nonlinear Analysis of Reinforced Concrete Joints with Bond-Slip Effect Consideration in OpenSees
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Original Article, C53 Keywords:Bond-Slip model, beam-column connection, OpenSees, Nonlinear analysis, Bridge |
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Experimental Study of Bell-Mouth Intakes on Discharge Coefficient
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Original Article, C54 ABSTRACT:The strong vortices at the mouth of an intake reduce the discharge efficiency. One of the solutions for controlling the vortex is the use of bell-mouth intakes. Since only general guidance for use of bell-mouth intakes is available a study for the more shapes of mouth of intake is needed. Hence, a comprehensive set of experiments have been carried out using 4 different mouth-shapes of a vertical intake. The results showed that with reducing the radius of curvature of bell-mouth intake, the coefficient of discharge rate increased, and maximum discharge coefficient with four different mouth shape of intake with the radius of curvature of 2d was created. |
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Study of Non-linear Dynamic Behavior of Structures with Steel Shear Wall under the Near Fault Earthquakes
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Original Article, C55 ABSTRACT:This paper deals with study of the steel shear walls and dynamic analysis of such structures under the earthquakes near fault. The studied frames in this paper have a span in 4-meter width and 3-meter height and are included 3 spans. We studied the dynamic of frames after modeling the frames in ABAQUS and giving the earthquake acceleration records near Kobe, Lomaprieta, and Northridge. The results showed that the increase of number of storey increases maximum storey displacement of moment frames. The increase of thickness the shear wall also will decrease the displacement of maximum storey because of decreasing the non-linear effects of shear wall and the delay on submission. Therefore, Base shear in moment frames of 3, 6, and 12-storey, not only depends on maximum acceleration and acceleration records, but also depends on the form of acceleration records. By increasing the number of the storey, this efficacy will be decreased so that the maximum acceleration would be more effective on the storey shear increase or decrease. We can say, by increasing the number of storey of vibration mode, maximum acceleration of storey has the regular process in each 3 acceleration record. It seems that the acceleration of storey not only is based on the type of acceleration record but also is based on the other elements such as increasing the thickness of shear wall and number of the storey. Maximum response in the last storey would not that change by increasing the thickness of shear wall but in the response of other storey, has 6 storey especially storey 3, 4, and 5 in the frame. We can conclude that acceleration of the storey compared to acceleration of column has had the increasing process, by watching the response of acceleration record. The increase of shear wall also decreases the acceleration of storey. |
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The Assessment of Road Network Vulnerability in Formal and Informal (slum) Urban Tissues to Earthquake Hazards With Crisis Management Approach (Case study: Zone 1 Tabriz)
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Original Article, C56 ABSTRACT:The urban road network is one of the main components of the city’s lifelines that especially after crisis play significant role including the rescue operation, evacuation of the wounded and ... So the analysing of the urban road network besides planning for reducing these harms, are inevitable. In this paper, to evaluate urban road networks vulnerability of Zone 1 of Tabriz, 3 main criteria of density, level of inclusion and building features were employed which each of these criteria are divided into some sub-criteria that these sub-criteria were weighted using Delphi method. Ultimately, after evaluation of roads vulnerability in terms of each criterion, the layers were overlaid using multi criteria evaluation. The obtained results show that, the roads network vulnerability in region 1(planned tissues) is lower than middle and about 61 percent vulnerability of them is very low. The very high vulnerability is observed mostly in informal settlements area that it is about 96 percent. |
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Optimization the Distance between Piles in Supporting Structure Using Soil Arching Effect
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Original Article, C57 ABSTRACT:High cost value of traditional methods for stabilization of pit, encouraged the engineers to study more about soil characteristics and its application. Arching effect is one of these characteristics, it allows to designers apply non-continuous structural elements to provide safety and economy of project. To investigate arching effect of retained structure with anchorage method, Plaxis 3D Tunnel software is used to model fine-grain (CL-ML) with hardening soil behaviour which simulate soil material. In first model, the distances between piles are 2m and number of anchors are 5. In second model, the distance between piles are 4m and number of anchors are 3. The numerical modeling results show horizontal arching appearance in distance between piles. A comparison between the results gained from the 3D FE analyses and the more or less conventional method shows that the classical method is very much on the safe side. |
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Optimization of Energy Consumption in Buildings with Architectural Design Compatible with Environment and Climate
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Original Article, C58 ABSTRACT:Extremely valuable fossil fuels and huge national investment in the recovery of fuel costs highlight the need to improve the structure and patterns, energy efficiency necessary to use. Damaging effects of fossil fuels on the environment and the nature have created risks in the lives of citizens, especially in today's metropolises. Thus, considering the use of native and adaptive knowledge in today architecture is crucial. Therefore, the present paper aims to investigate the environmental and climate effects on sustainable construction and constrains with the environments in hot and dry regions and its effect on optimization of energy consumption in the green architecture compatible with nature in city Damghan. Accordingly, besides use of library resources, required information was collected through field and descriptive –analytical methods in order to different aspects of climate effects on architecture and building in the studied region were considered. The obtained result indicate that traditional architecture consistent with Damghan climate, is totally in accordance with sustainable architecture principles and besides saving energy consumption, has a complete compatibility with the environment. |
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Evaluating Various Factors in Calculation of Scour Depth around Bridge Piers Using HEC-RAS Software, CSU2001 and Froehlich Equations
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Original Article, C59 ABSTRACT:Today, scour is one of the important issues in river and coastal engineering science. Most of the existing structures exposed to the flowing water are destroyed by this phenomenon. Determining relationship between parameters influencing scour depth and maximum depth of scour, and also finding dominant function of them is one of the important issues in hydraulic engineering. Many equations and software have been presented by researchers to calculate local scour, such as Hec-Ras software. Ignorable errors of this software in vitro test make it one of the nominated options in evaluating local scour depth. Hec-Ras software uses CSU and Froehlich (1991) equations to calculate local scour. In this study, software output and manual calculation output of CSU and Froehlich equations were compared. Results of empirical equations and Hec-Ras in the scattering length of Haraz River were compared with each other to create equal hydrological and hydraulic conditions. Reviewing the Froude number, its measurement, and the effective coefficients of common empirical equations and software has significant effect on changes of these parameters in the results. The study also indicate that equations used in Hec-Ras will have acceptable results if their coefficients are examined with sufficient engineering , accurate perspective and controlling use or non-use of coefficients in ranges closer to the defined boundary. |
