International Journal of Civil Engineering
Volume:10 Issue: 1, Mar 2012

In this paper, a location allocation (LA) problem in construction and demolition (C&D) waste management (WM) is studied. A bi-level model for this problem under a fuzzy random environment is presented where the upper level is the governments who sets up the processing centers, and the lower level are the administrators of different construction projects who control C&D waste and the after treatment materials supply. This model using an improved particle swarm optimization program based on a fuzzy random simulation (IPSO-based FRS) is able to handle practical issues. A case study is presented to illustrate the effectiveness of the proposed approach. Conclusions and future research directions are discussed.

Magnetic levitation (maglev) is amongst the most advanced technologies that are available to the transportation industries. It has already been noticed by decision makers in many countries around the globe. Contrary to such high levels of interest, there are no practical algorithms available to the engineers and/or managers to assist them in analyzing economics of the maglev systems. Therefore, it has been the purpose of this research to find appropriate answers to such vital questions and also investigate feasibility for practical use of maglev technology in rapid transit systems. The life cycle costs (LCC) for the maglev system including the cost of initiating such projects are included in this survey and are evaluated. To serve the purpose, an algorithm is presented that facilitates the technical and economical analyses of maglev systems. The proposal for a long distance maglev system, Mashhad-Tehran (M-T), is used as a case study by using the proposed algorithm. Moreover, the cost of establishing and operating M-T project is estimated in two different approaches. These include the already established mathematically based cost estimating method, and the cost estimations based on the international norms and standards. These standards are based on statistical (or provided) data. Such cost estimations assist verification of the proposed algorithm. Comparisons between outcomes of the three methods prove close agreement for the cost estimation by all of them. It is concluded that the proposed algorithm for implementation and operation of maglev route is practical.

Present study is an extension of earlier work carried out on two-lane two way roads in the two provinces of Pakistan i.e. N-25, N-55 and N-5 regarding the measure of operating speed and development of operating speed prediction models. Curved sections of two-lane rural highways are the main location of run-off road accidents. In addition to that the road alignment having combination of geometric elements may be more harmful to the drivers than the successive features with adequate separation. This study is carried out on two-lane two- way road along N-65 (from Sibi to Quetta). Three sections are selected for study with sixty three horizontal curves. Continuous speed profile data was recorded with the help of VBox (GPS based device) which was attached with a vehicle to detect vehicle position through satellite signals. VBox is new equipment with modern technology in this field and it helps in recording continuous speed profile and saving of this information on the computer as a permanent record. Through the regression analysis, models were developed for estimation of operating speed on horizontal curves and on tangent, and estimation of maximum speed reduction from tangent to curve. The validation of developed model shows compatibility with the experimental data.

In this paper the conditional location problem is discussed. Conditional location problems have a wide range of applications in location science. A new meta-heuristic algorithm for solving conditional p-median problems is proposed and results are compared to those of the previous studies. This algorithm produces much better results than the previous formulations.

This paper presents a strategy for using Harmony Search (HS) algorithm in facility layout optimization problems. In this paper an adapted harmony search algorithm is developed for solving facility layout optimization problems. This method finds an optimal facility arrangement in an existing layout. Two real-world case studies are employed to demonstrate the efficiency of this model. A comparison is also made to illustrate the efficiency of these strategies in facility layout optimization.

In almost all of the present mathematical models, the upstream subbasins, with overland flow as the dominant type of flow, are simulated as a rectangular plane. However, the converging plane is the closest shape to an actual upstream subbasin. The intricate nature of the governing equations of the overland flow on a converging plane is the cause of prolonged absence of an analytical or semi analytical solution to define the rising limb of the resulted hydrograph. In the present research, a new geomorphologic semi analytical method was developed that tries to establish a relationship between the parallel and converging flows to reduce the complexity of the equations. The proposed method uses the principals of the Time Area method modified to apply the kinematic wave theory and then by applying a correction factor finds the actual discharge. The correction factor, which is based on the proportion of the effective drained area to the analytically calculated one, introduces the convergence effect of the flow in reducing the potentially available discharge in a parallel flow. The proposed method was applied to a case study and the result was compared with that of Woolhiser's numerical method that showed the reliability of the new method.

Compared to conventional chlorination methods which apply chlorine at water treatment plant, booster chlorination has almost solved the problems of high dosages of chlorine residuals near water sources and lack of chlorine residuals in the remote points of a water distribution system (WDS). However, control of trihalomethane (THM) formation as a potentially carcinogenic disinfection by-product (DBP) within a WDS has still remained as a water quality problem. This paper presents a two-phase approach of multi-objective booster disinfection in which both chlorine residuals and THM formation are concurrently optimized in a WDS. In the first phase, a booster disinfection system is formulated as a multi-objective optimization problem in which the location of booster stations is determined. The objectives are defined as to maximize the volumetric discharge with appropriate levels of disinfectant residuals throughout all demand nodes and to minimize the total mass of disinfectant applied with a specified number of booster stations. The most frequently selected locations for installing booster disinfection stations are selected for the second phase, in which another two-objective optimization problem is defined. The objectives in the second problem are to minimize the volumetric discharge avoiding THM maximum levels and to maximize the volumetric discharge with standard levels of disinfectant residuals. For each point on the resulted trade-off curve between the water quality objectives optimal scheduling of chlorination injected at each booster station is obtained. Both optimization problems used NSGA-II algorithm as a multi-objective genetic algorithm, coupled with EPANET as a hydraulic simulation model. The optimization problems are tested for different numbers of booster chlorination stations in a real case WDS. As a result, this type of multi-objective optimization model can explicitly give the decision makers the optimal location and scheduling of booster disinfection systems with respect to the trade-off between maximum safe drinking water with allowable chlorine residual levels and minimum adverse DBP levels.

In this article, the two-dimensional depth-averaged Saint Venant equations, including the turbulence terms, are solved in a supercritical flow with oblique standing waves. The algorithm applies the finite volume Roe-TVD method with unstructured triangular cells. Three depth-averaged turbulence models, including the mixing length, and algebraic stress model (ASM), are used to close the hydrodynamic equations. The supercritical flow in a channel downstream from a side-baffle in plan is then simulated, and the numerical results are compared with the data obtained from a laboratory model. The application of different models demonstrates that the consideration of turbulence models improves the results at the shock wave positions. The qualitative study of the results and error analysis indicates that the ASM offers the most desirable solutions in comparison with the other models. However, our numerical experiments show that, amongst the source term components, the negligence of turbulence terms produces the least error in the depth estimation in comparison with the removal of the bed slope or bed friction terms.

This paper describes a numerical model and its finite element implementation that used to compute the cavitation effects on seismic behavior of concrete dam and reservoir systems. The system is composed of two sub-systems, namely, the reservoir and the dam. The water is considered as bilinear compressible and inviscid and the equation of motion of fluid domain is expressed in terms of the pressure variable alone. A bilinear state equation is used to model the pressure–density relationship of a cavitated fluid. A standard displacement finite element formulation is used for the structure. The Structural damping of the dam material and the radiation damping of the water and damping from foundation soil and banks have been incorporated in the analysis. The solution of the coupled system is accomplished by solving the two sub-systems separately with the interaction effects at the dam-reservoir interface enforced by a developed iterative scheme. The developed method is validated by testing it against problem for which, there is existing solution and the effects of cavitation on dynamic response of Konya gravity dam and Morrow Point arch dam subjected to the first 6 s of the May 1940 El-Centro, California earthquake, is considered. Obtained results show that impact forces caused by cavitation have a small effect on the dynamic response of dam-reservoir system.