Volume 3 : Issue 4, July 2013
Table of Content, 25 July 2013
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Photocatalytic Degradation of Air Emissions from Municipal Solid Waste Landfills
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Original Article, C21 ABSTRACT:This study examined the potential for photocatalytic oxidation to treat pollutants landfill gas (LFG). Three example LFG constituents were tested: methane, xylenes, and carbonyl sulfide. Methane, which comprises 40-60% of landfill emissions, is flammable and explosive at high concentrations, and is a greenhouse gas with global warming potential of 22 times that of carbon dioxide (100 year time horizon). Xylenes represent the second-highest concentration of hazardous air pollutants in LFG, and also contribute to ground-level ozone formation. Carbonyl sulfide was chosen as an example of a LFG constituent that is a hazardous air pollutant, as well as an odor-causing compound. Reaction rate constants are necessary for photocatalytic reactor design; accordingly, rate constants were determined for the compounds of interest over Degussa P-25 titanium dioxide (TiO2) catalyst in a continuous mixed-batch reactor. Plots of compound concentration versus time indicated first-order decay for all compounds tested. Destruction rates were higher for the smaller molecules methane and carbonyl sulfide and lower for the more complex xylenes. The destruction rates for methane were found to depend on relative humidity. The research concludes that photocatalytic oxidation is a potentially promising method to treat emissions from landfills. |
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Sediment load estimation by MLR, ANN, NF and Sediment Rating Curve (SRC) in Rio Chama River
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Original Article, C22 ABSTRACT:As the major part of river sediments is suspended sediment load, its estimation has important significance to manage of the water resources and environments. In this study, two conventional models: Sediment Rating Curve (SRC) and Multi Linear Regression (MLR) and two artificial intelligent models Artificial Neural Network (ANN) and Neuro-Fuzzy (NF) are applied to estimate suspended sediment load of the Rio Chama, a major tributary river of the Rio Grande, in the U.S. states of Colorado and New Mexico. Three statistical parameters–coefficient of determination (R2), root mean square error (RMSE) and Nash-Sutcliffe efficiency (NSE) are used to compare the results of models. The results showed that ANN using only discharge as input and NF model using both discharge and sediment as inputs have better performance than other two models. Furthermore, in this study, mentioned models are applied to evaluate annual sediment load and the best results have been achieved from NF and ANN respectively. Results of this study may be useful in picking up the most suitable modeling approach for similar studies in other river basins. |
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Study of slope stability and failure process of rock-fill barriers
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Original Article, C23 ABSTRACT:A rock-fill barrier is an economical and effective structure for flood routing as well as stabilizing river bed and banks. Rock-fill barrier is a permeable and flexible structure and could resist against forces due to flow through and over flow from this structure. This study was carried out to investigate the failure process and providing criteria for slope stability of rock-fill barriers. Eighty-eight laboratory tests were performed in a flume with a longitudinal slope of 0.003 m/m, width of 0.6m, height of 0.8m and length of 14 m. A dimensional analysis technique was used to develop equations for calculating values of depth of flow in the upstream side of the barrier, the maximum flow under which a barrier remains stable, and evaluation for downstream stability of side slopes in terms of discharge, gradation of material, standard deviation of material size and upstream and downstream water depths. Data from laboratory tests were used to evaluate the results of the new equations. Using the criteria of mean relative error and root-mean-square error, it is found that there is a good accuracy of the equations introduced in this research. |
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Determination of Energy Dissipation in Stepped Spillways Using Finite Element and Finite Volume Methods
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Original Article, C24 ABSTRACT:Accurate and suitable design of Spillways as major parts of dams is very important in the stability and safety of dams. In this study, flow over stepped spillway was simulated in 2D by solving poisson functions of stream and pressure in Finite Element method and with analyzing k-ε turbulence and volume of fluid models in Finite Volume technique. Also a comparison was done between the results of numerical models and measured values in order to investigate the accuracy of the models in calculation of energy dissipation. The relative error percent average of energy dissipation calculation using Finite Element and Finite Volume approaches was achieved 2.85% and 1.26%, respectively. Results showed Finite Volume approach could be employed slightly better than Finite Element method in modelling flow hydraulic over stepped spillway. |
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The Effect of Geometric Parameters and Foundation Depth on Scour Pattern around Bridge Pier
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Original Article, C25 ABSTRACT:Scour around bridge foundations is one of the major causes of serious damage to the bridge. In this study, the effect of shape, level and position angle of foundation on scour pattern was investigated experimentally. The experiments were conducted for 4 foundation shapes including; square, cylinder, aerodynamic along and across the channel, 5 foundation depths and 7 foundation alignments. The results show that the scour depth depends on the foundation depth, shape and foundation alignment to the approach flow. The best foundation shape which leads to minimum scour, was aerodynamic shape along the channel, square, aerodynamic across the channel and cylindrical shape, respectively. The results also show that positioning of foundation below the initial channel bed, leads to less values of scour depth around bridge pier. Also the best angle for positioning of foundation is zero, i.e. parallel to flow direction. Analyses of results also show that the appropriate level for positioning the foundation is 25 to 50 % pier diameter below the channel bed. |
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Optimal Cost Design of the Water Distribution Network Using the Meta-Heuristic Methods |
Original Article, C26 ABSTRACT:Today, optimal cost design of water distribution networks is one of the fundamental issues in water management plans. In recent years, high accuracy of meta-heuristic methods has gained attention of researchers. In this research, genetic algorithm and harmony search methods were used for optimal cost design of water distribution network in Kourtay village, Khoy. The results showed the significant ability of the methods, since the design costs were decreased by 8% and 10% using the genetic algorithm and harmony search algorithm, respectively. Furthermore, the Harmony search method was found more optimal and faster than the genetic algorithm. |
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The Study of Effect of Dredging and Dike Construction on the Flow Hydraulic and Reduction of Flood in Downstream of the River (Case Study: Karun River Downstream Between Ahvaz and Farsyat)
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Original Article, C27 ABSTRACT:The aim of this study is to simulate a numerical model for flood spreading and to control it in Karoun River in the downstream of Ahvaz to Farsyat which is affected by dredging and the construction of dike. Using the HEC-RAS 4.1 software, one-dimensional flow model in this field was simulated. After entering the data to the model and calibration, the model was run based on selected design flow rates, and water levels were calculated and areas of flood spreading were defined. Then, the mathematical model was run based on the dredging and dike construction. Due to lack of efficiency of dredging operations for flood control and the lack of a suitable location for deflecting flow, the only practical and cost-effective method for controlling the flood of the Karoun River in the studied interval is to construct a dike with designed height. |
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Experimental Study on the Flexural Behavior of Reinforced Concrete Beams as Replacement of Copper Slag as Fine Aggregate
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Original Article, C28 ABSTRACT:Researchers studied and developed waste management strategies to apply for advantages for specific needs. Owing to the scarcity of fine aggregate for the preparation of mortar and concrete, partial replacement of Copper Slag with sand have been attempted. The effects of replacing fine aggregates by copper slag on the compressive strength of cubes, split tensile strength of cylinders and flexural strength of beams are evaluated in this study. Copper slag is obtained as waste product from the sterlite industries. Investigations were carried out to explore the possibility of using copper slag as a replacement of sand in concrete mixtures. The test results of concrete were obtained by adding copper slag to sand in various percentages ranging from 0%, 20%. 40% 60%, 80% and 100%. All specimens were cured for 28 days before compression strength test ,splitting tensile test and flexural strength. The highest compressive strength obtained was 35.11MPa (for 40% replacement) and the corresponding strength for control mix was 30MPa. This results of the research paper showed that the possibility of using copper slag as fine aggregate in concrete. The results showed the effect of copper slag on RCC concrete elements has a considerable amount of increase in the compressive, split tensile, flexural strength characteristics and energy absorption characteristics. |
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Investigation and Evaluation of Artificial Neural Networks in Babolroud River Suspended Load Estimation
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Original Article, C29 ABSTRACT:Estimation of sediment load is a priority of the river management, dam's reservoirs and generally water projects. Because of nonlinear structure of sediment phenomena, the classical and common methods like sediment rating curve is not able to estimate sediment rate correctly. In recent years, artificial intelligence methods such as ANNs are recommended for solving the nonlinear problems and to achieve closer result to the actual data. In the present study, various combinations of flow discharge and sediment rate in present and past days were used as input parameters, while the suspended sediment load was used as output of the model. Then, by use of MATLAB software and different Neural Network such as MLP, RBF and GRNN, optimum architecture of networks is obtained based on four statistical indices viz. mean square error, mean bias error, modeling efficiency and determination coefficient for Ghoran Talar station in Babolroud River to compare with sediment rating curve. The results showed that MLP with combination of current discharge for estimate of current sediment has a better precision than other two neural networks. Also, the use of artificial neural network has a better performance than sediment rating curve method and recommended for river suspended load estimation. |
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The Importance of Determining Damage Levels of the Bridges in Non-Linear Dynamic Analysis
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Original Article, C30 ABSTRACT:During past earthquakes, different modes of damage were observed in bridges; consequently in seismic evaluation of these structures, various Indexes were used to determine vulnerability of the structures against earthquake vibrations. In this paper, damage indexes of structural elements of bridge are introduced and suggested definitions for structure damage state are stated. Then, a three span bridge is analyzed using OpenSees non-linear analysis software, considering three-dimensional model under earthquake load and non-linear behavior. After calculating necessary outcomes of the elements and nodes, damage indexes of damage at the foundations and columns level were measured. The model is able to calculate responses and damage indexes of supports and joints. Using this model, damage level of bridge structure is determined based on tables, which determine necessity of retrofitting. Based on the result, decisions made based on each criterion are compared. The results show that exact specification of damage indexes for the estimation of the vulnerability of structures (bridges here) is very important. |
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Forecasting Daily Stream Flows of Vaniar River Using Genetic Programming and Neural Networks Approaches
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Original Article, C31 ABSTRACT:This study compares three different artificial intelligence approaches, namely, gene expression programming (GEP), and artificial neural networks (ANN), in daily as well as monthly streamflow forecasting. Daily streamflow data from Vaniar River in the Northwestern Iran were used. Coefficient of determination, root mean square error and scatter index were used to compare simulation results. The study demonstrates that the optimal results were obtained from the triple-input models including streamflows of current and two previous days and that the GEP model performed better than the ANN model in daily streamflow forecasting. |
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Investigation of Dam Construction Effects without Environmental Assessment (Case Study: Urmia Lake)
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Original Article, C32 ABSTRACT:Feedbacks on numerous harmful problems in the environment have caused appearance of some human society’s sensitivity about the range of human’s non-limited activities in the environment which are done without considering environmental limitations during the economic development process in the recent decades. If environmental problems, along with technical and economic justifications are not considered, activities related to the water resources development program will result in irreparable and undesirable consequences. Drying up of the lake due to irregular exploitation of catchment basin water resources and construction of several dams on the branches of its rivers without environmental assessments have led to increase in the region’s temperature, appearance of sand and salt storms, destruction of potential agricultural land, flooding, change in cultivation pattern, hence jeopardizing the life of region’s people. Because of these, Natural ecosystems existing around the lake have been changed remarkably, and animates’ habitat in the lake is going to be destroyed. So, it is necessary to carry out an accurate evaluation before implementing water resources projects during the investigation of economic and technical justifications, so that any exploitation of nature can be done in the framework of the capabilities and potentials of natural environment. In this paper, we present some approaches to fight against undesirable consequences of dam construction, investigating environmental changes in Urmi a Lake. |
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Benchmarking of the Design Principles of Traditional Architecture
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Original Article, C33 ABSTRACT:Even though sustainable designing is the main discussion of nowadays architecture, all principles are practically concerned by our predecessors in ecological architecture. Traditional architecture of Iran considers tranquillity of interior space without utilizing energy consuming and pollutant devices and this architecture is very much capable of offering methods to use these kinds of energies and can be used for designing new monuments. Advancement in technology and improper use of this advancement has caused these techniques to be ignored and the non-recyclable fossil fuels to be used excessively. To replace clean energies with fossil fuels, regarding their high expenses and the risk to humans’ life, and to achieve sustainable architecture, old architecture of Iran shall be studied and their methods be used regarding the needs of present society. |
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Estimation of Channels Seepage using Seep/w and Evolutionary Polynomial Regression (EPR) modeling (Case Study: Qazvin and Isfahan Channels)
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Original Article, C34 ABSTRACT:Research and studies on the seepage of channels so far as man power and time and expense required for the experimental measurement of seepage canals or studies that require complex mathematical equations to solve difficult linear integral, need for a new and accurate way to predict the amount of seepage in canals before creation of it. Developing computer-based tools during the last two decades facilitates and develops of computational intelligence techniques. Seep/w and EPR are the new technique developed in recent years and at first it has been used for modeling environmental phenomena by providers. The use of these methods in water engineering has recently started and it is growing. However, in order to relative extent of these methods, collection efficiency in many ways remains a mystery. The results of modeling performed in seep/w for different initial conditions in canals including canal width, canal slope, water depth, the lining thickness, and depth to groundwater and accuracy of results on Qazvin and Isfahan canal were investigated. |
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An Assessment of a Modal Pushover Method Based On 2DOF Modal System for Tall Asymmetric-Plan Buildings
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Original Article, C35 ABSTRACT:Recently, a novel two-degrees-of-freedom (2DOF) modal system has been proposed by Lin and Tsai which considers bifurcating and interaction between modal translation and modal rotation. Also, they claim that the proposed system is accurate than the conventional single-degree-of-freedom (SDOF) modal system in estimating the seismic demands of asymmetric-plan buildings. In this paper, the efficiency of application of the proposed system for tall buildings is evaluated. Hence, a modal pushover analysis is performed for a sample tall asymmetric-plan building based on SDOF and 2DOF modal systems. Then, the seismic responses of building are estimated by utilizing nonlinear time history analysis (NTHA). Finally, the analytical results are compared. Results show that the efficiency of 2DOF modal system becomes considerable at high levels of building, in particular for rotational responses. Consequently, the new system may be an alternative to the SDOF modal system in estimating the seismic responses of asymmetric-plan buildings. |
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Increasing Development of the Cities and its Impact on the Environment
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Original Article, C36 ABSTRACT:Cities are physical structures that have been built in the heart of nature by human beings. The growth rate of urbanization has been increased after the industrial revolution and urban sprawls are considered some kind of invasion of natural spaces around the city. Currently converting natural areas to urban residential spaces and urban application, conversion of natural forests to agricultural land and villa construction and road building, uncontrolled growth of consumer industries, pollution of water sources, increased artificial uses of the Earth and environmental pollution, have caused a lot of damages to normal appearance of the Earth and continuation of this trend can cause the interaction of nature and consequently make life of current and future generation face to face with danger. Environment as a development platform has an important role in the development of the cities and healthy environment and sustainable ecosystems not only provide necessary platform in development process but also, the appropriate environment for human being to live in and his appropriate participation in the process of human development. Therefore any operation of the nature to construct and develop the cities should take place after evaluation of the resources and regarding the capacities of the natural environment. No city enjoys being completely prepared to guarantee its future sustainability and environmental requirements, force urban planners to observe the requirements of sustainable development. Accordingly, they should organize urban system and modes of production and methods of urban life such that urban development moves towards environmental sustainability. In sustainable urban development the subject of conservation of the natural resources for the present and future through optimal use of the land and causing the least damages to its resources are considered. |
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Dynamic characteristics of monthly rainfall in Tabriz under climate change
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Original Article, C37 ABSTRACT:Among the factors creating the changes in climate include ever-increasing population, changes in land usage and the development of industrial activities. Thus, studying the effect of this phenomenon on hydrological processes, in particular rainfall is considered as one of the most important issues concerning water engineering. Chaos theory is a tool that can be implemented besides other methods in modeling nonlinear, complicated hydrological phenomena like rainfall, due to its wonderful capabilities. In this study, monthly rainfall in Tabriz has been studied through this theory under historical and climate change conditions. In so doing, the statistical period of 1971 to the year 2000 was considered as the historical period, and the results obtained from the model LARS-WG were also considered under two scenarios in three future periods. The results indicated that historical period data having the fractal dimension of (5.96) has good chaotic nature. In the case of scenario A2, the data of all three series had good chaotic nature as well. In scenario B1, random investigation in all three periods will be appropriate. |
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