Volume 2 : Issue 2, March 2012

Table of Contents, 30 March 2012

Research Title/ Field

Article (Abstract)

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Local Prediction in River Discharge Time Series

Original Article, B9
Ghorbani MA, Daneshfaraz R, Arvanagi H, Pourzangbar A, Saghebian SM, Kaveh Kar SH.
Journal. Civil Eng. Urban.
2(2): 51-55. 2012.

ABSTRACT: In this paper, chaotic behavior of the daily river discharge time series from the Karoon River, during January 1999-December 2004 is investigated. The phase space, which describes the evolution of the behavior of a nonlinear system, is reconstructed using the delay embedding theorem suggested by TAKENS. The delay time used for the reconstruction is chosen after examining the first minimum of the average mutual information (AMI) of the data. It is found that a delay time of 40 days and the sufficient embedding dimension is estimated using the false nearest neighbor algorithm which has a value of 8 for the river flow time series. Based on these embedding parameters we calculate the average divergence rate of nearby orbits given by the largest Lyapunov exponent. The largest Lyapunov exponent 0.0255 for is estimated. In this study the local prediction model has been applied to predict daily discharge time series. In this prediction model, the dynamics of the system are described step by step locally in the phase space, the results are quite satisfactory.
Keywords
:
Chaos theory; Karoon River; Local Prediction; Lyapunov exponent; Time series

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Study and Comparison the Efficiency of Mualem- Van Genuchten and Brooks-Corey Models in Predicting Unsaturated Hydraulic Conductivity in Compacted Soils

Original Article, B10
Abbaspour H, Shorafa M, Daneshfaraz R, Mohammadi MH, Rashtbari M.
Journal. Civil Eng. Urban.
2(2): 56-62. 2012.

ABSTRACT: Soil hydraulic properties including soil water characteristics curve and hydraulic conductivity are two important properties to determination of water movement in soil. Hydraulic conductivity plays an important role in underground water movement, water flow to porous medium and pollutants transferring. Measuring these parameters in laboratory is costly and time-consuming. So, mathematical models were developed. Nowadays, numerous empirical models were presented to prediction of unsaturated hydraulic conductivity which of these models we can point out Gardner model, Campbell, Brooks-Corey and Mualem- Van Genuchten models. Present study was conducted on compacted soils in laboratory. Samples were collected from 0-10cm depth and Compaction created by proctor in six replication and four levels including C0 (control), C1, C2 and C3 by increasing in soil bulk density with the ratio of 5, 10 and 15%, respectively. Unsaturated hydraulic conductivity for these treatments evaluated and compared using Mualem-Van Genuchten (VG) and Brooks-Corey (BC) models by RETC software and identified that unsaturated hydraulic conductivity increased due to increase in fine pores as compaction increased and amount of correlation coefficients between moisture content and unsaturated hydraulic conductivity in BC model for all compaction treatments was more than those for VG model.
Keywords
: Brooks-Corey model, Mualem-Van Genuchten model, soil compaction, unsaturated hydraulic conductivity

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Numerical Study of Unsteady Laminar Flow around a Circular Cylinder

Original Article, B11
Keramati Farhoud R,
Amiralaie S, Jabbari Gh, Amiralaie S.
Journal. Civil Eng. Urban.
2(2): 63-67. 2012.

ABSTRACT: In this paper, Numerical study of incompressible and unsteady flow around a circular cylinder with Reynolds number=150 has been studied at different alternative vortex times. Flow has been studied via solution of Navier-Stokes and continuity equations with using of finite volume method. Flow Parameters including drag and lift coefficient, Strouhal number, velocity contours, pressure contours, pressure coefficients and vorticity contours are calculated in this work and were compared with other numerical and experimental results that show good agreement. Results have shown that flow in entrance boundary after passing cylinder is completely unsteady in spite of steady flow and also results have shown changes periodically and have minimum value in symmetry line in the computational domain.
Keywords
:
Unsteady flow- Finite Volume Method- Circular Cylinder- Strouhal number- Drag and Lift coefficient

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 Determination of the Most Important Parameters on Scour at Coastal Structures

Original Article, B12
Yeganeh-Bakhtiary A, Ghorbani MA and Pourzangbar
A.
 Journal. Civil Eng. Urban.
2(2): 68-71. 2012.

ABSTRACT: Scour at coastal structures is one of the major problems that may lead to their failure. Therefore, predicting accurate scour depth at coastal structures is important. Extensive laboratory studies have been conducted predicting the maximum scour depth. These studies have developed their formulas using the limited set of effective input parameters. This study presents an alternative to the conventionally regression-based equations in the form of genetic programming (GP) in order to predict the maximum scour depth at coastal structures under the action of breaking waves. To determine the effective parameters, different models with various combinations of input parameters were considered. Parameters such as reflection coefficient, relative water depth at the toe of the structure, the serf similarity parameter, Shields parameter and breaking wave steepness and the wave breaking depth were found to be best inputs. 46 data sets compiled from published literatures were used to train and test the networks or evolve the models. Statistical parameters including the root mean square error, determination coefficient, scatter index and BIAS are used to measure their performance. The results indicate that relative water depth at the toe of the structure plays a crucial role in the scour process.
Keywords
:
Coastal structures; breaking waves; Genetic programming; Scour depth; Regression-based equations.

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Numerical Investigation of Sluice Gates' Shape Factor on Contraction Coefficient

Original Article, B13
Sadeghfam S and Akhtari AA.
 Journal. Civil Eng. Urban.
2(2): 72-74. 2012.

ABSTRACT:The behavior of flow under sluice gate and determining the water profile is one of the important issues in hydraulic engineering. In this study the contraction coefficient is studied and the effect of slice gate's shape is observed numerically by CFD model. The turbulence model k-e (RNG) and unsteady flow mode are used in analysis of two dimensional gates. Three types of slice gate's shapes are analyzed and contraction coefficient of these cases is presented and compared with experimental and theoretical results of other researchers. It is worth mentioning that for these cases the equations in terms of the ratio of gate opening to depth of approaching flow behind gate, are collected. So the gate's shape has significant role on contraction coefficient and between 3 types of gate's shapes that are investigated in this research, contraction coefficient of the sluice gate with shape of two side slope (case 3) has larger amount of this coefficient.
Keywords
:
Sluice Gate, CFD model, Contraction Coefficient, Turbulence Model k-e (RNG)

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Assessment of Travel Characteristics in Akure Metropolis

Original Article, B14
Fajugbagbe A, Aderinlewo O and Croope S.
 Journal. Civil Eng. Urban.
2(2): 75-79. 2012.

ABSTRACT: The travel characteristics of commuters in Akure Metropolis were obtained in terms of trip destinations, travel modes, capacity of vehicles used, number of vehicles and the frequency of trips. The travel distance, travel time and cost of travel were also measured. It was found that an average 9,391 intercity trips were generated daily from Akure Metropolis to various destinations out of which Lagos has the highest number of person trips. 77.54% and 22.46% of the total trips were made by bus and car respectively. The socio-economic status of the people was analyzed quantitatively and qualitatively. The analysis results show that people with an average income ranging from N20,001 to N30,000 travel most with public vehicles while people between the ages of 31 and 50 make the highest number of trips. Regression analysis of the trips generated in terms of the travel characteristics produced a model which explained the data to an accuracy of 98.7%.

Keywords: Socio-Economic, Travel Modes, Regression Analysis

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The evaluation of the geo-tourism for urban development: A case study in Ajabshir city, Iran

 Original Article, B15
Tavallaei S, Rashidi Ebrahim Hesari A, Fathi MH, Farzaneh M, Mousavi SCh.
Journal. Civil Eng. Urban. 2(2): 80-85. 2012.

ABSTRACT: Tourism development based on natural and geo-tourism attractions have been among the study targets of urban regional planners during past decades. It is obvious that Feasibility studies as well as the evaluation of urban tourism potentials are being considered as first phase of tourism planning. The major objective of this study is to investigate the geo-tourism capabilities and limitations of Ajabshir city and to develop the best strategy toward improving and enhancing tourism management and development for the city in this region. For this purpose, SWOT strategy planning method was used based on identification of weaknesses and strengths points (internal factors) and opportunities and threats (external factors). Furthermore, Likert spectrum was used to rank the internal and external factors in order to come up with SO, WO, ST, WT strategies. The study suggests that the region has a high potential regarding tourist attraction. The internal factors of this study (point3.05) indicate that the strength points of the region are more than the weakness points. In addition, the matrix of the evaluation of the external factors (point2.72) shows that the opportunities of the region are more than its threats. It further argues that the macro strategies the tourism of the region and thus this city must be developed in such a way to make the best use of the local possible opportunities. This study further suggests that by taking advantage of Ajabshir's tourism potential in general and Geo tourism attractions in particular, along with adaption of an appropriate tourism strategies, the city could well utilizes these opportunities.
Keywords:
Geo-tourism, urban development, Ajabshir city, SWOT

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