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Eurasian Soil Science - In this study, we developed a general mathematical relationship to determine hydraulic tortuosity. An optimization code was run in MATLAB R2014a software, using Monte Carlo... 相似文献
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A model for optimal allocation of water from a single-purpose reservoir to an irrigation project with pre-determined multiple cropping patterns was developed. The model consisted of two modules: (I) the intra-seasonal allocation model (non-linear programming) which is used for allocation of water among different crops for a definite combination of state variables (inflow class, rainfall class, reservoir storage classes at the beginning and at the end of the season) for the non-dormant season to maximize total farm income; and (II) the seasonal allocation model (stochastic-dynamic programming) which is used for the convergent operating policy over seasons for optimal expected farm income over a year. The model was applied to Ardak reservoir dam (I.R. Iran) in an arid region. Low river inflow in the dormant season at the study area could not admit the reservoir class changes for specific combinations of state variables, and therefore resulted in a non-usable result. Imposing a fictitious positive relative net benefit for all possible combinations of reservoir class changes eliminated this problem. It was also shown that rainfall did not play a marked role in the study area, which is an arid region, and its stochastic nature can be removed from the model. 相似文献
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Mohammad Reza Kandehkar Ghahraman Hossein Hosseini-Nave Omid Azizi Mohammad Reza Shakibaie Hamid Reza Mollaie Samane Shakibaie 《Iranian Biomedical Journal》2021,25(3):193
Background:There is limited information on the 3D prediction and modeling of the colistin resistance-associated proteins PmrA/B TCS in Acinetobacter baumannii. We aimed to evaluate the stereochemical structure and domain characterization of PmrA/B in an A. baumannii isolate resistant to high-level colistin, using bioinformatics tools. Methods:The species of the isolate and its susceptibility to colistin were confirmed by PCR-sequencing and MIC assay, respectively. For 3D prediction of the PmrA/B, we used 16 template models with the highest quality (e-value <1 × 10−50). Results:Prediction of the PmrA structure revealed a monomeric non-redundant protein consisting of 28 α-helices and 22 β-sheets. The PmrA DNA-binding motif displayed three antiparallel α-helices, followed by three β-sheets, and was bond to the major groove of DNA by intermolecular van der Waals bonds through amino acids Lys, Asp, His, and Arg, respectively. Superimposition of the deduced PmrA 3D structure with the closely related PmrA protein model (GenBank no. WP_071210493.1) revealed no distortion in conformation, due to Glu→Lys substitution at position 218. Similarly, the PmrB protein structure displayed 24 α-helices and 13 β-sheets. In our case, His251 acted as a phosphate receptor in the HisKA domain. The amino acid substitutions were mainly observed at the putative N-terminus region of the protein. Furthermore, two substitutions (Lys21→Ser and Ser28→Arg) in the transmembrane domain were detected. Conclusion: TheDNA-binding motif of PmrA is highly conserved, though the N-terminal fragment of PmrB showed a high rate of base substitutions. This research provides valuable insights into the mechanism of colistin resistance in A. baumannii. Key Words: Acinetobacter baumannii, Amino acid substitution, Colistin, Mutation 相似文献
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Use of a water deficit sensitivity index for partial irrigation scheduling of wheat and barley 总被引：2，自引：0，他引：2
Shortage of water is the most important limiting factor for crop production in the arid and semi-arid regions in Iran. More
land can become productive by using partial irrigation at strategic times during the growing season. This may be accomplished
if a proper index of crop sensitivity to water deficit at various growth stages is used. A theoretical procedure was applied
to determine the savings in water and the economic benefit derived from partial irrigation, using a water stress sensitivity
index for winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) in a dry region of Fars province in Iran. The results indicated that some water reduction is possible. In general, the
suggested maximum allowable water reduction was unreasonably high for the sensitivity index (λ
i
) proposed by Nairizi and Rydzewski. Their index is not applicable in arid and semi-arid areas. However, the field-derived
λ
i
of Aryan resulted in a reasonable water reduction close to the field-applied water reduction to achieve a corresponding relative
yield. Therefore, appropriate values of λ
i
for different climatic conditions should be used to calculate rational water reductions. The maximum allowable water reduction
for spring barley was higher than that for winter wheat. The reduction increased as the benefit to cost ratio (B/C) was increased. Water reductions of 7 and 26% were allowed for winter wheat and spring barley, respectively, at a B/C ratio of 1.5. This corresponded to an 8 and 35% increase in cultivated area, respectively. These results need to be validated
in more extensive field experimentation.
Received: 9 December 1994 相似文献
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The Effects of Irrigation Efficiency and Uniformity Coefficient on Relative Yield and Profit for Deficit Irrigation 总被引：2，自引：1，他引：2
To avoid constructing expensive hydraulic structures for implementing new water resources, a deficit irrigation project may be designed to optimise the use of the available water resources. Previously, irrigation efficiency and uniformity coefficient have not been considered quantitatively. In fact, efficiency is a very significant factor in optimisation analysis, and the potential for increasing irrigation efficiency is one of the key reasons for deficit irrigation. In this paper, the influences of irrigation efficiency under full irrigation condition ηf on the performance of deficit irrigation, and the effects of deficit irrigation on improving the irrigation efficiency under deficit irrigation ηd have been considered for four crops of winter wheat, spring barley, maize, and sorghum in an arid region of Iran. Furthermore, the combined effects of irrigation efficiency and uniformity coefficient on deficit irrigation were investigated. Results showed that considerable improvements can be achieved in water use efficiency under this concept. Some mathematical relationships were derived to show the quantitative increase in irrigation efficiency under deficit irrigation. These results showed that the performance of deficit irrigation is highly dependent on ηf, such that lower ηf values result in higher allowable water reduction level and also more field income. By combined analysis, water reductions for sorghum and barley were found to be economically feasible at values of irrigation efficiency lower than 1·0, while water reduction for maize was not economically feasible at irrigation efficiencies greater than 0·6. Water reduction for wheat was economically feasible at irrigation efficiencies of 0·6 or lower. 相似文献
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