The benthic macroinvertebrate communities in the confluence areas from tributaries to mainstream could play an important role in understanding interactions between materials flows from rivers and their ecological consequences. Based on monitoring on conducted in the four typical tributaries (Huangshui River, Fenhe River, Weihe River and Luohe River) to the Yellow River during spring and autumn in 2015, the characteristics of macroinvertebrate communities are systematically compared. As results, sorted by the number of macroinvertebrate species in both seasons for all confluences, Luohe River (28)>Huangshui River (26)>Fenhe River (23)>Weihe River (17). Moreover, the collecter-gather becomes dominant functional feeding group in both seasons for all confluences except scraper dominated in autumn in Luohe River. Detrended Correspondence Analysis (DCA) reveals that substrate is of significance in structuring benthic macroinvertebrate communities. The survival of aquatic plants seems more favorable to survival of benthic macroinvertebrate. Furthermore, Redundancy Analysis (RDA) suggests that benthic macroinvertebrate communities are mainly influenced by pH and conductivity. The present study provides new information on species composition, density, biomass, functional feeding group of benthic macroinvertebrate communities, and the relationship between macroinvertebrate communities and habitat factors, which would be of particular use to deeper understand the aquatic organism in the Yellow River receiving tributaries, which are interfered to various degree by human activities.
In order to solve the problems such as large computation and high requirement of geometry in the traditional 2D ISS (inverse scattering series) method, the 1.5D ISS deghosting method is proposed after dimensionality reduction from 2D ISS method. The examples of data study show that the 1.5D method can save lots of calculation and also degrade the requirement of geometry. 1.5D ISS method does not need any subsurface information and wavelet estimation, and it is suitable for different kinds of complex structure and low signal to noise ratio seismic data. Besides, the 1.5D ISS method can remove the ghosts from marine seismic data effectively and enhance resolution; simultaneously it will expand the frequency band and compensate the null frequencies energy.
Based on the chlorinated organic compounds pollution existed in underground water of China, Zero-Valent-Iron (ZVI) technology is employed for the removal of four representative halogenated organic compounds (HOCs) (tetrachloroethylene, PCE; tricholoroethylene, TCE; tetrachlormethane, TCM; and chloroform, CT). The results indicated that the reduction rates of four target compounds, of which the initial concentration is 400 μg/L, negatively correlated with the size of Zero-Valent-Iron particles. The reduction kinetics of the targeted HOCs were all well fitted with the Pseudo-firstorder kinetics, and the ranking of obtained first order rate constants (K) among different particle sizes was K20nm>K100nm>K10μm>K100μm. Comparing K among four target HOCs, the reduction rates of chlorinated methane (CT, TCM) are higher than chlorinated ethylene (PCE, TCE), and highly chlorinated HOCs (PCE, CT) were degraded more easily than lower one (TCE, TCM). pH of aqueous solution all increased along the chlorinated compounds reduction which was raised by the reaction between ZVI and water. The oxygen in water consumed the ZVI particle either and competed with the surface adsorbed chlorinated compounds. In summary, Zero-Valent-Iron proved to be an efficient technology for typical HOCs removal, which can be considered as a promising process added in the beginning part of drinking water treatment plant.
Based on constraint Euler-Lagrange equations, a general dynamic model is presented for power converters with multiple or single switches. From the research on the energy of power converters, the generalized charges and generalized currents coordinates of dynamic elements are chosen, switching function is introduced, and a set of differential algebraic equations with constraint can be obtained based on Euler-Lagrange equations with the Kirchhoff’s current constraints. The inductor currents and the capacitor voltages are chosen as the state variables, and then the state equations of the converters can be got ultimately. The proposed method is applied to model an ?uk converter circuit with an ideal switch and a three phase PWM rectifier with multiple switches. From the modeling process, it can be seen that this method is unified, clear in physical meaning and strong commonality. Finally, with the obtained state equations, the working process of ?uk converter is simulated in MATLAB, the simulation results coincide with the operation of the power converter, and it verify the effectiveness of the proposed method, which has higher application value to model the more complex power converters.