Characteristic Study of Briquette Cyanobacteria as Fuel in Chemical Looping Combustion with Hematite as Oxygen Carrier

Due to the more and more serious cyanobacteria bloom problem, it is particularly urgent to find a technology suitable for large-scale disposal and the efficient recovery of abundant nitrogen and phosphorus resources in cyanobacteria. The combination of chemical looping combustion (CLC) and biomass densification technology is thought to be a promising utilization selection. Based on the experimental results, the mechanical strength and energy density of briquette cyanobacteria are evidently increased with the compressive load; whereas, 10% is the optimal moisture content in the densification process. A higher heating rate in TGA would result in the damage of the internal structure of the briquette cyanobacteria, which are conducive to the carbon conversion efficiency. The presence of a hematite oxygen carrier would enhance the carbon conversion and catalyzed crack liquid products. CO2 yield is increased 25 percent and CH4 yield is decreased 50 percent at 900 °C in the CLC process. In addition, the lower temperature and reduction atmosphere in CLC would result in a lower NO emission concentration. The reactivity and porous property of hematite OC in CLC also increased during 10 redox cycle experiments. The CLC process accelerates the generation of CaH2P2O7 and CaHPO4 in cyanobacteria ash, which is more conducive to phosphorus recovery

Quadrotor UAV flight control via a novel saturation integral backstepping controller

In this paper, in order to reduce the influence on quadrotor flight from different external disturbances, a novel nonlinear robust controller is designed and used in the quadrotor system. At first, a nonlinear dynamic model of the quadrotor is formulated mathematically. Then, a quadrotor flight controller is designed with the method of classical backstepping control (CBC) and the nonlinear system using this controller is proved to be asymptotically stabilized by the Lyapunov stability theory when there is no external disturbance. At last, a new nonlinear robust controller established by the introduction of both the saturation function and the integral of error into CBC is designed and named as saturation integral backstepping control (SIBC). The boundedness of the nonlinear system under external disturbances is verified by the uniformly ultimately bounded theorem of the nonvanishing perturbation. The numerical simulations of hovering and trajectory tracking are carried out using MATLAB/SIMULINK taking the external disturbances into consideration. In addition, a series of outdoor flight experiments were completed on the actual experimental equipments of quadrotor UAV under the time-varying disturbance from wind. According to the simulation and flight experiment results, the proposed SIBC strategy shows a superior robustness than CBC and integral backstepping control (IBC) strategy

Rank classification method for cascade reservoirs considering scale, benefits, and risk consequences

Cascade reservoirs are essential in water resource utilization, flood control, and disaster mitigation. They have been built in several rivers worldwide. The rank classification for cascade reservoirs has significant practical implications for resource distribution decisions and risk management strategies and is also essential for ensuring the security of the basin. Internationally, reservoirs are typically classified based on project scale and dam failure consequences, whereas the risk transmission and superposition effect renders the classification method of reservoirs not directly applicable to cascade reservoirs. Therefore, to address this issue, this study proposed a rank classification method for cascade reservoirs. First, based on the scale, benefits, and risk consequences of dam failure, an index system for the rank classification of cascade reservoirs was established. Second, by constructing social risk criteria for cascade reservoirs and establishing a link among “project rank-reliability index-annual failure probability,” the allowable dam failure losses for different project ranks were determined. Thereafter, considering risk transmission and superposition, the rank classification standard and index quantification method for cascade reservoirs were proposed. Finally, five cascade reservoirs were selected for a feasibility study. The proposed method provides a supplement to the current rank classification standard of water conservancy projects in China and can also serve as a reference for risk assessment and classification management of cascade reservoirs in other countries.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Safety and Security Scienc