Growing water scarcity, due to growing populations and varying natural conditions, puts pressure on irrigation systems, which often are the main consumptive water users. Therefore, water resources management to improve the allocation of limited water supplies is essential. In this study, a non-linear programming optimization model with an integrated soil/water balance is developed to determine the optimal reservoir release policies and the optimal cropping pattern around Doroudzan Dam in the South-West of Iran. The proposed model was solved using a genetic algorithm (GA). Four weather conditions were identified by combining the probability levels of rainfall, evapotranspiration and inflow. Moreover, two irrigation strategies, full irrigation and deficit irrigation were modeled under each weather condition. The results indicate that for all weather conditions the total farm income and the total cropped area under deficit irrigation were larger than those under full irrigation. In addition, our results show that when the weather conditions and the availability of water changes the optimal area under corn and sugar beet decreases OPEN ACCESSWater 2014, 6 3069 sharply. In contrast, the change in area cropped with wheat is small. It is concluded that the optimization approach has been successfully applied to Doroudzan Dam region. Thus, decision makers and water authorities can use it as an effective tool for such large and complex irrigation planning problems.

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Background: The use of casting ring to produce accurate casting has been challenged with the introduction of a ringless casting technique. This study compared the vertical margin discrepancy of castings fabricated with the ringless technique, conventional (ring and liner) technique and conventional technique with hygroscopic expansion investment systems. Objectives: The current study aimed to determine and compare the mean values of vertical margin discrepancies of castings in three investing procedures: the ringless technique and conventional investing technique. Materials and Methods:In the first step, 39 coping wax patterns for Porcelain fused to metal restoration (P.F.M). With chamfer finish line were fabricated on the metal die and then divided into three groups of 13. The first group used conventional investing (with ring and liner), the second group used the ringless technique and the third group used the conventional ring technique with liner and hygroscopic expansion. All groups were invested using Thermovest phosphate bonded investment. Then wax patterns were cast with Ni-Cr alloy (super cast). Castings were divested, cleaned and seated on the metal die after minimal internal surface adjustment. The vertical margin discrepancy was measured in four sites: on the buccal, lingual, mesial and distal surfaces of the die. Castings were measured on an optical microscope. The vertical margin discrepancy in each group was used for statistical analysis. Results: After statistical evaluation, the following results were obtained: the mean vertical margin discrepancy for conventional investing was 156.72 ± 64.67µ; for the ringless technique it was 117.3 ± 26.77µ; and for the conventional metal ring technique with hygroscopic expansion it was 96.15 ± 38.31 µ. There is a significant difference between castings of the conventional investing technique and the ringless and ring plus hygroscopic expansion techniques (P < 0.001). No significant difference was found between the ringless and ring plus hygroscopic expansion techniques (P = 0.183). Conclusions:The castings fabricated from the ringless technique with non-precious alloy are acceptable. This investing system is useable for the fabrication of fixed restorations.