Evaluating soil nitrate dynamics in an intercropping dripped ecosystem using HYDRUS-2D.

The competition mechanisms between crop species for water and nutrients, especially nitrate (NO3-N), in intercropping ecosystems are still poorly understood. Therefore, an experiment involving high (300 kg ha-1 for corn and 250 kg ha-1 for tomato), medium (210 kg ha-1 for corn and 175 kg ha-1 for tomato), and low (150 kg ha-1 for corn and 125 kg ha-1 for tomato) N-fertilizer applications (HF, MF, LF, respectively) was conducted in the corn and tomato intercropping ecosystem during 2014 (a calibration period for modeling) and 2015 (a validation period for modeling). The modified HYDRUS-2D code was used to analyze soil NO3-N concentrations (SNC) in the middle between corn rows (Pc), between corn and tomato rows (Pb), and between tomato rows (Pt), NO3-N exchange in the horizontal direction between different regions, NO3-N leaching from the corn, the bare, and the tomato region, and N uptake by crops. Simulated SNCs were in good agreement with measurements, with RMSE, NSE, and MRE of 0.01-0.06 mg cm-3, 0.75-0.98, and 8.7-19.1%, respectively, during the validation period (2015). Average SNCs in the 0-40 cm soil layer were different between Pc, Pt, and Pb. Intensive NO3-N exchange in the horizontal direction occurred during the second stage (Day After Sowing [DAS] 37-113 in 2014; DAS 29-120 in 2015). NO3-N exchange between the corn and bare regions was lower than between the tomato and bare regions due to smaller concentration gradients. However, in the vertical direction, NO3-N leaching from the corn region in both years was 4.1 and 8.8 times larger, respectively, than from the tomato region under HF since NO3-N mainly moved from the tomato region to the corn region. Our results reveal the competition between corn and tomato for N and provide a rationale for formulating and optimizing different fertilizer regimes for different crops in the intercropping ecosystem

Developing High-Throughput Chemical Approaches For Proteomic Profiling Of Aspartic Proteases And Protein Kinases

Ph.DDOCTOR OF PHILOSOPH

Dynamic behavior analysis and time delay feedback control of gear pair system with backlash non-smooth characteristic

The present work investigates the non-smooth vibration characteristic and time delay feedback control of a gear pair system involving backlash and time-varying mesh stiffness. Firstly, a gear pair model with backlash non-smooth characteristic is established. Then in combination with the discontinuity mapping method, Floquet theory is presented to determine the stability and bifurcation of periodic response, and the period doubling bifurcation has been accurately predicted. Moreover, the maximal Lyapunov exponent is obtained to determine the chaos state in gear pair system which is conform to the bifurcation diagram and Poincare section. Finally, a time delay feedback is introduced to control the dynamic behaviors of the system, and numerical simulation results show that the system can be effectively controlled from chaotic motion into stable periodic motion by increasing the delay feedback gain or delay time

Study on Modification of Lignin as Dispersant of Aqueous Graphene Suspension and Corrosion Performance in Waterborne G/Epoxy Coating

Though graphene (G) as an excellent protective material for metal, it can aggravate metal corrosion in other side. The modification of sodium lignin sulfonate was achieved by using itaconic acid and acrylamide，which was proved by UV-vis and Raman spectra. The modified sodium lignin sulfonate (LAI) with more carboxylic groups can be used as the dispersant for aqueous graphene suspension. The commercial graphene can be dispersed uniformly and stability in water via π-π interaction with LAI at high concentration (6 mg/mL)，and the LAI-G system can be used as an inhibitor in waterborne epoxy coatings too. Electrochemical impedance spectroscope (EIS) and Tafel polarization curves showed that the corrosion performance of waterborne epoxy system with well-dispersed G (0.5 wt %) was remarkably improved compared with pure epoxy coating

Field assessment of basin irrigation performance and water saving in Hetao, Yellow River basin: issues to support irrigation systems modernisation

Research PaperWater-saving irrigation needs to be implemented in Hetao irrigation district to help satisfying the demand by other users in the Yellow River basin. Aiming at assessing the potential irrigation performance and water saving at farm level, a set of traditional basins and another of precision-levelled basins cropped with maize, wheat and sunflower and managed by farmers were evaluated. Data were collected to characterise the basin sizes, microtopography, inflow rates, advance and recession times, cut-off time and soil water content. In addition, families of infiltration curves were derived from field observations and subsequent use of model SIRMOD. Infiltration was higher for the precision-levelled basins and decreased from the first to the next irrigation events. Infiltration data were used to support the computation of distribution uniformity (DU), beneficial water use fraction (BWUF) and deep percolation (DP). For traditional basins, DU and BWUF were low and DP was high. When precise land levelling was practised, DU increased greatly to near 94% but BWUF improved little, because irrigation scheduling was inadequate leading to excessive water application; however, non-negligible water saving was achieved for maize and wheat since they have higher irrigation demand. In contrast, simulating the application of an appropriate irrigation scheduling through adjusting the cut-off time led to an approximately unchanged DU but BWUF greatly increased and DP reduced to 10% on average. This condition represents a potential water saving of 34e39%; however its achievement requires improved design of farm systems, appropriate irrigation water deliveries and scheduling, and the support and training of farmersinfo:eu-repo/semantics/publishedVersio