اثر درصد همپوشاني مجموعه هاي فازي بر روي شاخص خاك در شهر آبيك استان قزوين

The effect of overlapping percent for fuzzy sets on soil index in Abyek town of Qazvin province

مدل تعيين شاخص خاك با استفاده از روش منطق فازي و سيستم استنتاج ممداني طراحي شد. اين تحقيق در بخشي از اراضي شهرستان آبيك استان قزوين انجام شد. در اين مدل فازي هشت خصوصيت خاك جهت بررسي تناسب آن براي محصول گندم با كمك سيستم اطلاعات جغرافيايي مورد بررسي قرار گرفت. مجموعه هاي فازي هر يك از خصوصيات بر اساس نيازمندي هاي محصول گندم تهيه گرديد و جهت بررسي اثر مقادير موجود نزديك مرزهاي كلاسها بر خروجي سيستم استنتاج فازي درصدهاي هم پوشاني مختلفي شامل صفر 40،30،20،10 و 50 به مجموعه هاي فازي اعمال شد. نتايج نشان داد كه با افزايش درصد هم پوشاني مجموعه هاي فازي، دقت رابطه افزايش يافت. به طوري كه در رابطه شاخص خاك و عملكرد محصول گندم، هم پوشاني 50 درصد مجموعه هاي فازي، بيشترين ضريب تعيين 0/93 را به خود اختصاص داد. بنابراين درصد هم پوشاني مجموعه هاي فازي اثر قابل توجهي بر روي دقت مدل داشت. نقشه منطقه و كلاس واحدهاي خاك نيز در درصدهاي مختلف هم پوشاني مجموعه هاي فازي بدست آمد و با همديگر مقايسه شدند.

Model of soil index determination was designed using fuzzy logic and Mamdani inference system. This research was done in Abyek town in Qazvin province. In this fuzzy model, eight properties of soil were investigated to evaluate the suitability of soil for winter wheat using GIS. Fuzzy sets of each property were prepared based on the requirements of the winter wheat. Different percentage of overlapping for fuzzy sets as 10, 20, 30, 40 and 50 were applied to the fuzzy sets for studying the effect of values near the boundary on the output of fuzzy inference system. The results showed that the accuracy of the model was changed by increasing the percentage of overlapping fuzzy sets. So that the overlapping of 50% for fuzzy sets were allocated the highest coefficient of determination (R2= 0.93) in the relationship between soil and yield of wheat. Thus the percentage of overlapping for fuzzy sets had a significant effect on the accuracy of the model. Classification map of soil units were also obtained in different percentage of overlapping for fuzzy sets and compared with each other