عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Earthquake, as one of the most important natural disasters, release large energy suddenly in a short time. It takes place on the crust because of babel. Earthquake may release decades, centuries or thousands of blocked energy in less than one minutes (Gibson 1997).
After earthquake happens, quick and on-time relief play an important role to reduce human casualties. It is an important problem to choose an optimum route in order to access to the damaged areas. The purpose of this paper is to choose the best route to relief by considering the effective actions in waste of time of auxiliary vehicles. For this, first the relief expert chooses some proposed routes to relief before coming to the damaged area using 3D designed model of the area. Then, weights are assigned to each of this parameters using Ordered Weighted Averaging (OWA) operator. This operator provides the expert an idea on how to apply his points to determine the best route. This case becomes to the weighting equations as an optimism factor. Finally, the proposed routes are compared based on the probability of blocking and waste of time, and thus the user can choose the best route.
Determining the optimum route to relief in earthquake is the issue that is studied and discussed by experts and specialist because of high importance for years. So far, a lot of papers have been published about this problem, especially in Iran. These papers study how to choose an optimal route in earthquakes in different ways. However, the âheightâ has not been considered as an important parameter to choose an optimal route after the earthquake. As the buildings are destroyed in earthquakes, the route is blocked by breached material of the existing building on route. To have a more realistic estimation, the height of the building must be considered as an important factor in determining the best route. Another advantage of the algorithm presented in this paper is using Ordered Weighted Averaging (OWA) operator. This algorithm allows to relief expert who has knowledge of the disaster area, and to include influential considerations to assign weights to various parameters. This interference is applied into the equation as a multiplier called optimism factor.
As mentioned, in this paper, four parameter of distance, street width, height and buildings age are examined to find the best route to the disaster area. However, before evaluation, it is necessary to determine some routes as proposed. In this paper the study area is part of Tehran.
- Proposed routes
To choose some proposed route, a 3D model of the area is prepared and provided to the relief expert. The expert selects four proposed routes by using the model as well as their knowledge of the area. It should be mentioned that the 3D model will help to choose the best proposed routes. For example, it may be the case two different routes, have the same width of streets, but they are different in building heights. In this case, the expert, with respect to the knowledge and observations, can choose routes as proposed route that have merit as an optimal route. Figure 1 shows a 2D view of the four proposed routes chosen by the expert.
Study of the four main parameters influencing the choice of the optimal route
Having proposed routes identified, the main factors that influence the choice of optimal route should be examined.
Distance between reliefs and disaster area on each route, was measured and recorded.
B) Width of streets
Each route is composed on various streets with different widths. In this paper streets are divided into two types of streets (more than 6 meters width and less than 6 meters).
C) Buildings height
There are long and short buildings with different heights at each route. In this paper, buildings are divided into two types of buildings (more than 10 meters in height and less than 10 meters).
D) Buildings old
Buildings age is another important factor in choosing the optimal route. Because an old buildings is more likely to fail, thereby blocking the route. In this paper, buildings age are divided into two types of buildings (older than 15 years and less than 15 years).
Ordered Weighted Averaging operator is used for choosing the best route. In this operator a weight is assigned to each of the four parameters using an existing equation. The important point in this equations is that there is a parameter as optimism degree that can be determined by experts and it is necessary to briefly explain. Optimism degree is a number between zero and one. When the expert considers âoneâ for optimism degree, it means that the expert is optimistic. For example, one expert believes that if all buildings are greater than 10 meters height on a route, but even there is one building with less than 10 meters height, the conditions are ideal. However, if expert considers âzeroâ for optimism degree, it means that the expert is pessimistic. For example, one expert believes that if all buildings on a route are less than 10 meters in height, but even there is a building with 10 meter height, the route is not suitable.
In this paper, the weight of the various parameters for the optimism degree are considered (i.e., 0, 0.25, 0.5, 0.75 and 1) and finally, the results are compared.
In this paper, first, four proposed routes are chosen by using the 3D model of the disaster area for relief. Then, four parameter of distance, height and width of streets as well as buildings age were evaluated in each route. Then, the weight of each parameter was calculated according to the optimism degree.
The results of the calculation of weights for different optimism degrees for all the parameters are listed in Table 1.
Table 1 - Weight of parameters based on different optimism degrees
0 , 0.04 , 0.09 , 0.23 , 0.34 , 0.41 , 0.58 0
0 , 0.05 , 0.13 , 0.20 , 0.27 , 0.34 , 0.43 0.25
0.15 , 0.15 , 0.15 , 0.15 , 0.15 , 0.15 , 0.15 0.5
0.43 , 0.34 , 0.27 , 0.20 , 0.13 , 0.05 , 0 0.75
0.58 , 0.41 , 0.34 , 0.23 , 0.09 , 0.04 , 0 1
The following diagram is calculated after the obstruction.
Diagram 1 - Level of route blocking based on optimism degree for each route
The chart clearly shows that, the route #1 in all optimism degrees is the best route and has the lowest blocking.