Optimization of two-component composite armor against ballistic impact
Using Florence's model we determined an optimal design of a two-component ceramic-faced lightweight armor against normal ballistic impact. The solution is found in a closed form that allowed us to determine the thicknesses of the plates in the optimal armor as functions of the specified areal density of the armor, parameters determining the material properties of the armor's components and characteristics of the impactor.
Optimum Design of Ceramic-Composite Armors Against Ballistic Impact of Projectiles by Genetic Algorithm
One of the most important issues in passive defence is the design of bullet penetration resistant structures and panels. Two-component ceramic-composite armors are widely used in the bulletproof panels. In the recent decades, optimum design of thickness and material of ceramic and composite has been seriously considered by ballistic experts. Florence analytical model provides a good prediction of ballistic limit velocity of ceramic-composite armors. In this paper, based on the Florence and Bendor model, an effective methodology for optimum design of two-component ceramic-composite armors is presented, by a genetic algorithm solving technique. The design goal is achieving a minimum areal density for a given ballistic limit velocity of armor. The criterion is having the highest level of protection. In this method, material and thickness of ceramic and composite layers are considered as the design parameters. Using the results of the optimal solution, armors are designed to be resistant against two types of bullets with 7.62 and 12.7 mm caliber for different distances from target to firing place.
Using Fuzzy-Delphi technique to determine the concession period in BOT projects
BOT projects are affected by several risks and uncertainties. One of the most important issues in this type of contract is to determine the length of concession period considering these uncertainties. The previous studies have developed several models to determine the concession period. However, the uncertainties are not taking into account in most of the previous works. Moreover, none of the previous researches has the capability to aggregate the opinions of different experts being involved in a project regarding the values of the uncertain input parameters. In this research, a Fuzzy-Delphi technique is implemented to determine the length of concession period considering uncertainties. Using the proposed Fuzzy-Delphi technique, the values of different uncertain factors affecting a BOT project is determined considering opinions of a group of experts. The NPV value is calculated considering the resulted aggregated values of uncertain input parameters. Finally, the concession period is determined using fuzzy approach. A case study is conducted to evaluate the performance of the proposed methodology. It is shown that the concession period is determined more effectively using the proposed approach.