In the research, available sulphur in 4 700 soil samples was tested and analyzed in 2006-2007 in Dengzhou, and the results showed that available sulphur was insufficient in farmlands in Dengzhou for cereal crop and ab...In the research, available sulphur in 4 700 soil samples was tested and analyzed in 2006-2007 in Dengzhou, and the results showed that available sulphur was insufficient in farmlands in Dengzhou for cereal crop and about 60% farmlands with available sulphur belong to the farmlands with potential shortage of available sulphur for Cruciferae, Liliaceae and Leguminosae. Meanwhile, the producing causes were analyzed from the perspectives of fertilization structure and planting structure and the countermeasures were proposed in terms of sulphur movements in plants and characters.展开更多
In standard data envelopment analysis （DEA） models, inefficient decision-making units （DMUs） should change their inputs and outputs arbitrarily to meet the efficient frontier. However, in many real applications of...In standard data envelopment analysis （DEA） models, inefficient decision-making units （DMUs） should change their inputs and outputs arbitrarily to meet the efficient frontier. However, in many real applications of DEA, because of some limitations in resources and DMU＇s ability, these variations cannot be made arbitrarily. Moreover, in some situations, undesirable factors with different disposability, strong or weak disposability, are found. In this paper, a DEA-based model is proposed to determine the relative efficiency of DMUs in such a restricted environment and in presence of undesirable factors. Indeed, variation levels of inputs and outputs are pre-defined and are considered to evaluate the performance of DMUs. Numerical examples are utilized to demonstrate the approach.展开更多
文摘In the research, available sulphur in 4 700 soil samples was tested and analyzed in 2006-2007 in Dengzhou, and the results showed that available sulphur was insufficient in farmlands in Dengzhou for cereal crop and about 60% farmlands with available sulphur belong to the farmlands with potential shortage of available sulphur for Cruciferae, Liliaceae and Leguminosae. Meanwhile, the producing causes were analyzed from the perspectives of fertilization structure and planting structure and the countermeasures were proposed in terms of sulphur movements in plants and characters.
文摘In standard data envelopment analysis （DEA） models, inefficient decision-making units （DMUs） should change their inputs and outputs arbitrarily to meet the efficient frontier. However, in many real applications of DEA, because of some limitations in resources and DMU＇s ability, these variations cannot be made arbitrarily. Moreover, in some situations, undesirable factors with different disposability, strong or weak disposability, are found. In this paper, a DEA-based model is proposed to determine the relative efficiency of DMUs in such a restricted environment and in presence of undesirable factors. Indeed, variation levels of inputs and outputs are pre-defined and are considered to evaluate the performance of DMUs. Numerical examples are utilized to demonstrate the approach.
