RESUMO
The traditional path optimization problem is to consider the shortest path of the vehicle, but the shortest path does not effectively reduce the logistics cost. On the contrary, in the case of one-sided pursuit of the shortest path, it may cause some negative effects. This paper constructs a more realistic path optimization model on the path of traditional logistics distribution, and designs a path model based on simulated annealing algorithm which taking fuel consumption, cost, road gradient and condition of vehicle into account. The algorithm model of load capacity and other problems is used to verify the algorithm of the model through a simulation case of multiple distribution points. The experimental results show that the path optimization strategy considering the gradient of the road reduces the cost of the vehicle path, indicating the correctness of considering the vehicle load and road gradient factors in logistics transportation.
RESUMO
Fly ash was investigated as a raw material for the preparation of a composite coagulant with sulfuric acid. Types of acid solution, H2SO4 concentration, ratio of H2SO4 to fly ash and stirring time were respectively examined as factors that influenced the efficiency of converting the iron and aluminum components into a composite coagulant and coagulation performance on domestic wastewater. The coagulant was attained at the condition of H2SO4-fly ash ratio of 5 mL/g, H2SO4 of 2 mol/L, stirring time of 4h and stabling time of 30 min, and contained Fe3+ of 0.010 8 mol/L with conversion efficiency of 11.4% and Al3+ of 0.035 4 mol/L with conversion efficiency of 4.3%. Removal efficiencies of COD and SS by this type of coagulant reached 70.4% and 91.9% respectively when treating domestic wastewater. This study provides a promising means to utilize fly ash for coagulation, which possibly makes wastewater treatment more economical and more sustainable.