فهرست مطالب

  • Volume:32 Issue:12, 2019
  • تاریخ انتشار: 1398/09/10
  • تعداد عناوین: 15
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  • Leila Davarpanah *, Elham Abdollahzadeh Sharghi Pages 1696-1703
    The presence of particles such as algae, clay, organic materials and water-soluble substances often create turbidity or color in water. In recent years, electrocoagulation process has attracted an extensive attention due to its advantages. Since sand filters are widely used in water treatment industry and their corresponding backwash water is large in volume, turbidity removal will save water consumption and its recycling. In this study, real samples of backwash water from sand filters of a water treatment plant in Alborz province were collected. The turbidity removal was further evaluated under operating conditions of 6, 12, 18 and 30 V as the exerted voltages, electrode distances of 1 and 1.5 cm, different initial turbidities (391 NTU as sample 1 and 175 NTU as sample 2), iron and steel as the sacrificial electrodes in a continuous electrocoagulation reactor. According to the results, the optimum conditions without considering the process economy was found to be 30 V, the iron electrode and electrode distance of 1 cm and samples 1 and 2 had an effective turbidity removal efficiency of 98.4 and 91.6%, respectively.
    Keywords: Electrocoagulation, energy consumption, Sand Filter Backwash Water, Turbidity Removal, Voltage
  • Dmitriy Martyushev * Pages 1704-1709
    In the oil industry, the issue of controlling paraffin deposits remains relevant today. The most common way in the Perm Krai to remove paraffin is to lower the scrapers into the well.  This method is the main in the fight against paraffin deposits, but does not provide absolute protection. The least costly way to control paraffin is to use flushing with hot oil or water, but it does not always provide sufficient efficiency. Accordingly, for the selection of effective technology for each particular well, it is necessary to know the depth of wax deposition, the intensity and thickness of the formed layer. To solve this problem, modeling was performed in the OLGA software product of paraffin deposits in the wells of Perm Krai deposits. Based on the calculations performed in the OLGA software product, recommendations are given on choosing a method for removing paraffin deposits from the analyzed wells. The proposed measures for the removal of paraine deposits were implemented in the wells and showed significant efficiency. At three wells, a change in annulus pressure led to a decrease in foaming. The main problem was solved - paraffin in the annulus is not formed.
    Keywords: Bottomhole Pressure, Paraffin Deposits, Software Product OLGA, Tubing
  • Rezvan Behfar, Reza Davarnejad *, Rouhollah Heydari Pages 1710-1715
    In this study, Chemical Oxygen Demand (COD) from a pharmaceutical wastewater (PhW) was reduced by several techniques such as electro-Fenton (EF), photo electro-Fenton (PEF) and activated sludge (AS) processes and the obtained data were compared with each other. The effects of several parameters such as pH, current density, H2O2/Fe2+ molar ratio, volume ratio of H2O2/PhW, reaction time and UVA light were studied on the COD reduction through the EF and PEF processes. The Box-Behnken Design (BBD) under Response Surface Methodology (RSM) was applied to design and then optimize these processes. The optimal conditions for 87% of COD removal through the EF process were at pH of 3.27, current density of 57 mA/cm2, H2O2/Fe2+ molar ratio of 3.5, volume ratio of H2O2/PhW of 1.34 ml/l and reaction time of 56.32 min while the optimal conditions for 91.6% of COD removal through PEF process were at pH of 3.5, current density of 57.5 mA/cm2, H2O2/Fe2+ molar ratio of 3.81, volume ratio of H2O2/PhW of 1.5 ml/l, reaction time of 10.12 min and 6 W UVA light while 77.70% of COD removal was obtained by  the AS process with residence time of 1020 min. According to the kinetic study, the second order reaction (with high R2 data) could properly model the EF and PEF processes.
    Keywords: Activated sludge, COD removal, Pharmaceutical wastewater, Photo Electro-Fenton, Response Surface Methodology
  • Sedigheh Mohamadi *, Mohsen Saeedi, Afsaneh Mollahosseini Pages 1716-1725
    This work aims to investigate the competitive time-dependent desorption rate of heavy metals (lead, zinc, nickel) coexisting with phenanthrene from natural high buffering soil. Two non-ionic surfactants (Tween 80 and Brij 35) combined with disodium ethylene diamine tetraacetate salt (Na2-EDTA) were utilized as the reagents. The contaminants’ time-dependent desorption data was fitted with five kinetic models including parabolic diffusion, Elovich, fractional power function, pseudo-first and -second-order equations. The best removal of contaminants obtained by the mixture of Tween 80/EDTA; desorbing 93% of lead (Pb). The competitive desorption of nickel (Ni) and zinc (Zn) is affected by the stability of Metal-EDTA complexes. Moreover, phenanthrene removal in the soil studied was slow and laborious. The desorption kinetics are well described by parabolic diffusion (for phenanthrene) and pseudo-second-order (for heavy metals of interest). In the soil-surfactant-water system, soil structure changes were negligible; however, Tween 80 influenced the development of crystal faces of CaCO3 during the process.
    Keywords: Ethylene Diamine Tetraacetate, Heavy-metal, Kinetic, Soil, Surfactant
  • Abbas H. Mohammed *, Raad D. Khalaf, Taha K. Mohammedali, Ali K. Hussin Pages 1726-1732
    There have been great developments in the area of civil engineering in the recent few decades and among these, construction and material innovation are quite prominent. Steel-concrete composite construction has emerged as one of the fastest methods of construction. Even though considerable research efforts on conventional reinforced concrete columns have been executed prior to now, concrete filled steel tube (CFST) composite columns however have received limited attention. This work aims to study the experimental behavior of steel tubular specimens.  Plastic and steel specimens are considered with circular and square sections filled with the concrete with the steel fiber and as well,  plain concrete. Four parameters are considered in this study which are sectional designs (circular and square), tube thickness (2 and 5 mm), tube material (plastic and steel) and content of steel fiber (0 and 5%). Ten concrete filled steel tubular columns were cast and tested. Two circular columns were made from plastic and the other made from steel. The main purpose of this work are study the effect of steel fiber and cross section on the ultimate load capacity of columns. It was discovered the utilization of steel fiber reinforced concrete filled steel tubular columns have comparatively substantial stiffness in comparison with plain concrete filled columns.
    Keywords: Steel Tube, Concrete, Steel Fiber, Axial loading, Columns, Composite
  • Sajjad Mohsenzadeh, Ahamd Maleki *, Mohammad Ali Yaghin Pages 1733-1744
    Various experimental studies have been carried out on glass fiber reinforced concrete (GFRC), but in limited studies, the behavior of this type of concrete is evaluated using finite element method (FEM). In this study an analysis model is presented for predicting energy absorption capacity of glass fiber reinforced self-compacting concrete (GFRCSCC) beams and the results are compared with experimental study. For this purpose, the investigations are conducted in two experimental and numerical sections. In experimental section, the characteristics of fresh and hardened concrete have been evaluated using slump flow, V-funnel, L-box, T50, compressive strength, tensile strength and flexural strength tests. In numerical section, ABAQUS software has been used to simulate GFRCSCC beams. The concrete damage plasticity model has been used to simulated concrete material. The fiber contents are 0, 0.25, 0.75 and 1% of the mixed concrete by volume. The results show that the maximum increase in energy absorption capacity of beams compared to the plain concrete for 25, 35 and 45 concrete grade was 29, 33.2 and 53.75%, respectively. At last, the ultimate loads corresponding to the FEM are found to hold good agreement with experimental ultimate loads which validates the FEM.
    Keywords: beams, Energy Absorption Capacity, Finite element model, Glass Reinforced Concrete, Self-Compacting Concrete
  • Praveen Oggu *, Mehulkumar Pithadiya, Gopikrishna K Pages 1745-1752
    Reinforced concrete frame buildings with Open Ground Story (OGS) are one of the most common building configurations in urban habitat. These configurations are known to be vulnerable to seismic excitations, primarily due to the sudden loss in strength in the ground story and differential stiffness distribution throughout the structure. The differential stiffness distribution is attributed primarily to the interaction of non-structural infill wall with the moment-resisting frame. Hence, the interaction of infill wall needs to be accounted in estimating the seismic vulnerability. Therefore, the present investigation is focused on understanding the impact of utilizing real ground motion records on the performance assessment of RC buildings with and without consideration of infill walls. Fragility curves were developed for low and mid-rise structural models using Capacity Spectrum Method (CSM) specified by ATC-40 and with Incremental Dynamic Analysis (IDA). CSM uses the response spectrum specified by the respective code, unlike IDA where an ensemble of spectrum compatible real ground motion accelerograms satisfying the necessary site conditions is used in assessing the performance. Further, significant variations observed in the developed fragility curves by CSM and IDA emphasizes the sensitivity of real ground motion data in performance assessment.
    Keywords: Capacity Spectrum Method, Damage Probability Matrices, Incremental Dynamic Analysis, Open Ground Story Buildings, Seismic Fragility, Seismic Performance
  • Seyedamin Mostafavian *, Seyed Rasoul Nabavian, Mohammad Reza Davoodi, Bahram Navayi Neya Pages 1753-1761
    The output data from a structure is the building block for output-only modal analysis. The structure response in the output data, however, is usually contaminated with noise. Naturally, the success of output-only methods in determining the modal parameters of a structure depends on noise level. In this paper, the possibility and accuracy of identifying the modal parameters of a simply supported beam in the presence of noise has been discussed. The output-only modal analysis method with frequency domain decomposition was used and output data with various noise levels were considered. Initially, finite element modal analysis was used to determine the modal parameters for the beam which were afterwards enforced as the reference modal parameters. Then, appropriate input was applied to the beam and the acceleration signals of different nodes were produced through finite element transient analysis. In order to simulate noisy data, noises with different power levels were generated and added to the signals. Finally, the modal parameters were obtained by frequency domain decomposition method. The results showed that the modal parameters corresponding to the first vibration mode could only be identified with acceptable validity at low to moderate noise levels, whereas for higher modes, the modal parameters can be correctly obtained even at high noise levels.
    Keywords: Frequency Domain Decomposition, Modal Parameters, Noise level, Output-only Modal Analysis, Simply Supported Beam
  • Amin Iraji * Pages 1762-1772
    A previously introduced two phase model was used to assess its capability in predicting the behavior of reinforced soil walls under working stress conditions. The two phase model is a homogenization method based on the virtual work theorem. The reinforced soil medium is considered as the superposition of two continuous phases, the reinforcement and matrix phases that interact within the medium. Application of the two phase model simplifies changes in the arrangement and properties of the inclusions and decreases the computation time considerably. This approach can be used to reduce the time needed for optimization in practical applications. The introduced approach was first validated by comparison with the filed measurements. Therefore, a full-scale reinforced soil wall that has been constructed and tested under working stress condition at the Public Works Research Institute in Japan was simulated using the two phase model. A finite difference code was used to implement the two phase model and simulate the model. A nonlinear elasto-plastic law and a linearly elastic, perfectly plastic constitutive law were employed for the matrix and reinforcement phases, respectively. Then an extensive parametric study including 125 reinforced soil wall models was conducted to show the capability and strength of the introduced approach for simulation of the reinforced soil walls under working stress condition. The effect of inclusion length and stiffness, inclusion spacing, and wall height on maximum lateral displacement of the models was investigated. Eventually, a new dimensionless design parameter was introduced to achieve a simple criterion for evaluating lateral displacements.
    Keywords: New Design Parameter, non-linear behavior, Parametric study, Reinforced Soil Wall Displacement, Two Phase Model, Working Stress Condition
  • Jalal Al, Obaedi * Pages 1773-1780
    Traffic simulation represents an effective tool for evaluating the suggested alternatives to enhance traffic conditions prior to their application in real sites. U-turn sections represent examples of the complicated sections that cannot be analyzed properly without applying microsimulation approach.  Recently, in Iraq, speed humps were applied in prior to the merging locations and U-turn sections to enhance traffic safety.  However, the characteristics of traffic at U-turn section with the presence of speed humps have got little attention in previous literatures. This paper uses VISSIM microsimulation model to emulate traffic movements at selected U-turn sites in the cases of with and without speed humps.   Three median U-turn sites have been selected where two of these sites have speed humps prior to the turning locations.  Real traffic data have been obtained from these sites using video recordings to estimate specific parameters.  The developed simulation models were successfully calibrated and validated with the real data.  The models have been used in testing different scenarios including the effect of having different locations/ types of speed humps and finding the capacity of U-turn sections. The results showed that closer the speeds hump to the turning location is lower the time spent for merging.  The time spent values are increased with the increasing of traffic speeds at humps.  Higher capacity value is obtained for the site with an auxiliary lane and speeds hump compared with the other sites.
    Keywords: Microsimulation, traffic calming, U-turn, Speed Humps, travel time
  • Nasrin Mehranfar, M. Hajiaghaei Keshteli, Amir Mohammad Fathollahi Fard * Pages 1781-1789

    Nowadays, there is a great deal of attention for regulations of carbon emissions to enforce the decision-makers of production and distribution networks to redesign their systems satisfactorily. The literature has seen a rapid interest in developing novel metaheuristics to solve this problem as a complicated optimization problem. Such difficulties motivate us to address a production-distribution network design problem considering carbon emissions policies among the first studies in this area by a novel hybrid whale optimization algorithm. Accordingly, a mixed integer non-linear programming model has been developed. To tackle the proposed problem, a new hybrid metaheuristic based on whale optimization algorithm and simulated annealing as a successful optimizer is employed to solve the proposed problem. The calibration of the algorithms has been designed by Taguchi method, comprehensively. Finally, an extensive analysis has been evaluated through a comparative study along with some assessment metrics of Pareto solutions.

    Keywords: Production-Distribution Networks, optimization, carbon emissions, Nature-inspired algorithm, Whale Optimization Algorithm, Simulated Annealing
  • Faezeh Bagheri, Abdul Sattar Safaei *, Mostafa Kermanshahi, Mohammad Mahdi Paydar Pages 1790-1797
    To enhance agility and quick responding to customers' demand, manufacturing processes are rearrenged according to different systems. The efficient execution of a manufacturing system depends on various factors. Among them, cell design and human issue are the pivotal ones. The proposed model designs cellular manufacturing systems using three objective functions from three different perspectives, to reflect a more realistic picture of the cell formation problem. This paper presents a model with the goals of maximizing the total value of grouping efficacy and minimizing the total costs and total non-interest workers in cells in a dynamic environment for several consecutive periods.  The main idea of the proposed model is enhancing cell efficiency through an assigning the group of workers who have a mutual interest in working with each other. For solving the current model, the revised multi-choice goal programming method has been employed. Finally, computational results and sensitivity analysis are discussed.
    Keywords: Dynamic Cellular Manufacturing Systems Group Efficiency, Revised Multi-choice Goal Programming Method, Worker Interest
  • Gbeminiyi Sobamowo, Obanishola Sadiq, Saheed Salawu * Pages 1798-1804
    The dynamic behaviour of a circular plate in contact with fluid and resting on two-parameter elastic foundations is of interest in the field of geotechnics, structure, highway, railway, oil and gas and mechanical engineering. In this work, the dynamic behaviour of circular plate in contact with fluid and resting on Winkler and Pasternak foundations is investigated. The coupled differential equation of the system is analysed using differential transformation method. Good agreements are established when the results of the analytical solutions are compared to the results of the experimental investigation as reported in literature. The analytical solutions obtained are used to investigate the effects of elastic foundation parameters on natural frequency, combine foundation parameters on natural frequency, plate in contact with fluid and that of radial and circumferential stress on mode shapes. From the results, it is observed that, increases in elastic foundation parameter increases the natural frequency in all cases. Presence of fluid reduces the natural frequency of the plate. Also, it is established that mode shapes are not altered by the presence of fluid. However, mode shape displacement occurs due to presence of radial and circumferential stresses. Since the study provides a physical insight into the vibration mode of the structure, it is expected that the study will enhance better understanding on the dynamic behaviour of a circular plate in contact with fluid and resting on two-parameters elastic foundation.
    Keywords: Circular plate, Deflection, Free vibration, Winkler, Pasternak Differential Transformation Method
  • M. Dastagiri *, P Srinivasa Rao, P Madar Valli Pages 1805-1812
    Electro Discharge Machining (EDM) is a noticeable machining practice among created unconventional machining procedures for intricate, complex profiles in "hard to machine" materials, similar to heat-treated steels, composites, superalloys, ceramics, composites, carbides, and so on. In EDM, the material expulsion of the cathode is accomplished through precise controlled electric discharge (the spark), which transforms the metals of two electrodes into melt and vaporize, and due to the breakdown of the dielectric medium.  In this research work, the suitability of non-edible plant seed oils from Pongamia pinnata as a dielectric fluid in the EDM process was investigated. Also, the suitability of EDM oil as an alternate dielectric fluid for industrial application was studied. Electrode Wear Rate (EWR), Material Removal Rate (MRR), Surface Roughness (SR), and Tool Wear Rate (TWR) are the key performance features of EDM. The principal goal of EDM is to get higher MRR alongside accomplishing the sensibly good surface quality of the machined workpiece. The parameters that accomplish the most astounding MRR depend on the machining surface, which is related to the workpiece and tool. Dielectric is the most significant variable for obtaining excellent results for the above-stated key features. These investigations showed that Pongamia pinnata oil is a suitable dielectric media; the results are satisfactory comparing with that of EDM oil. The effect of topography of the workpiece and carbon particles dissolving is also checked with SEM analysis for any deviations on work surface.
    Keywords: Electric Discharge Machine, Material removal rate, Tool wear rate, Electrode Wear Rate, Surface roughness, TOPSIS
  • Somaye Narrei, Majid Ataee Pour * Pages 1813-1822

    Metal price is one of the most important parameters in the calculation of cut- off grade. The cut- off grade has the main role in determination of mine layout. Mine layout actuates mineable reserve, mine life and economic profitability. Not considering the uncertainty in metal prices can lead to a non-optimal layout. In this paper optimum underground mine layout is determined by expected utility theory with regard to metal price uncertainty. With the proposed approach metal price uncertainty is modeled by Monte Carlo simulation technique and decision maker will be gained probability of underground mine layouts. The utility function of underground mine layouts is defined and by the probability of them, expected utility is determined. Underground mine layout with the maximum expected utility is the optimum layout. Application of this approach in a hypothetical gold mine, in addition to considering metal price uncertainty, leads to 14% more mineable reserve and 18% higher net present value than normal design.

    Keywords: Cut- Off Grade, Mineable Reserve, Monte Carlo simulation, Price Uncertainty