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This paper investigates a passivity-based hierarchical SM control (PBHSMC) approach to solve the trajectory tracking issue of a special class of UMSs using unmeasured states and in presence of both unmatched and matched perturbations. First, a passivity-based SM observer (PBSMO) is designed for quick estimation of states in the UMS. Then, we develop a nonlinear two-layer switching surface using feedback passivation. The passivation-based approach ensures global asymptotical convergence of tracking error on the switching surface with the discontinuous term. Moreover, we develop an SMC law that can satisfy reaching mode and sliding mode conditions. Finally, to illustrate the performance of theoretical results, the developed control scheme is assessed by numerical simulation of two case studies including flexible-joint manipulator (FJM) and underactuated surface vessel (USV) systems. The simulation results indicate the superiority of the PBSMO-based PBHSMC scheme over the conventional SMO-based HSMC in suppressing unwanted oscillations of link, low tracking error and overshoot, short settling time, smooth and small control efforts, and also more accurate estimation of state variables with less chattering. [ABSTRACT FROM AUTHOR]

This study was performed to investigate the effect of various fertilizers and tillage systems on seed yield, oil quality, and seed elements of sunflower (Shams cultivar). The experiment was conducted in a split-plot design with three replications at research field of University of Zabol (Chahnimeh) in 2019 and 2020. The main factor included three tillage methods (A1: moldboard plow + disc, A2: chisel plow + disc and A3: disc). Subfactor includes six fertilizer combinations :(B1: no fertilizer application, B2: 100 kg/ha of diammonium phosphate, B3: 25 tons/ha of livestock manure +100 kg/ha of diammonium phosphate, B4: 50 tons/ha of livestock manure +100 kg/ha of diammonium phosphate, B5: 25 tons/ha of livestock manure, B6: 50 tons/ha of livestock manure). Results showed that in the first year, the highest seed yield (5072 Kg/ha) and percentage of oleic acid (51.61%) was achieved from A3B6. In the second year, the highest seed yield (8003 Kg/ha) with A1B5 and the highest oleic acid (53.87%) was obtained from A2B2. Application of A2B2 treatment composition produced the highest nitrogen content in the seed (0.625%) and application of A3B6 produced the highest potassium content in the seed (11.652 mg/g). In general, by considering the reduction of tillage in the field and improving the traits of sunflower, the application of A3B6 is recommended to improve the percentage of oleic acid, phosphorus, and potassium contents and 1000-seed weight and if the conventional tillage is used, B2 can be recommended to improve seed yield, calcium content, and oil content. [ABSTRACT FROM AUTHOR]

Organic and biological fertilizers are considered as a very important source of plant nutrients. A field experiment was conducted during 2017−2018 in paddy soil to investigate the effect of vermicomposting of cattle manure mixture with Azolla and rice straw on soil microbial activity, nutrient uptake, and grain yield under inoculation of N2-fixing bacteria. Experimental factors consisted of organic amendments at six levels (vermicomposts prepared from manure (VM); manure + rice straw (VRM); manure + Azolla mixture (VAM); manure + rice straw + Azolla mixture (VRAM); raw manure without vermicomposting (M), and a control) and N2-fixing bacteria at three levels (Azotobacter chroococcum, Azospirillum brasilence, and non−inoculation). The results showed that, vermicompost treatments compared to control and raw manure significantly increased the number and biomass−C of soil microorganisms, urease activity, number of tillers hill−1, phosphorus (P) and potassium (K) uptake, and grain and protein yield. Inoculation of plants with N2-fixing bacteria, especially Azotobacter increased the efficiency of organic amendments, so that the maximum urease activity, soil microbial activity, P and N uptake, and grain yield (4,667 (2017) and 5,081 (2018) kg/h) were observed in vermicompost treatments containing Azolla (VAM and VRAM) under inoculation with Azotobacter. The results of the study suggested that, using an organic source along with inoculation with appropriate N2-fixing bacteria for vermicompost has a great effect on enzyme activity, soil biology, nutrient uptake and grain yield has a synergistic interaction on agronomic traits under flooded conditions. Therefore, this nutrient method can be used as one of the nutrient management strategies in the sustainable rice production. [ABSTRACT FROM AUTHOR]

This study aims at investigating the effect of organic growth stimulator on growth and yield of rapeseed (Dalgan cultivar) under drought in University of Zabol (Chahnime) during 2017 as a split plot experiment, based on RCBD with three replications. The treatments include irrigation cut off levels, based on the phenological growth stages (Sylvester-Bradley encoding system): I1 = control (complete irrigation), I2 = irrigation up to growth rate code 2.20 (twenty internally identified), and I3 = irrigation to growth rate code 5.9 (all pods are more than 2 cm long), with the subsidiary factor being consisted of four levels of fertilizer: F1 = control (pure water solution), F2 = Hamoon Green 1 liter at 10 liter + calcium, F3 = Hamoon Green 1 Liter at 20 liter + calcium, and F4 = Hamoon Green 1 liter at 30 liter + Calcium. Results show that I2 has significantly decreased plant height, stem diameter, number of pods, number of seeds per pod, 1000-seed weight, grain and biological yield, and oil percentage, while F2 has increased the abovementioned traits, except for the percentage of oil. Interaction effects show that the highest amount of chlorophyll a, b, total, carotenoid, selenium, and calcium content of grain belong to I1F2, while the highest amount of proline has been observed in I2F2. Also, the highest of these traits belongs to F2. Generally, spraying the organic growth stimulator can moderate the harmful effects of drought stress in rapeseed, improving the seed yield by 27%. [ABSTRACT FROM AUTHOR]