Reasonable distribution network planning schemes can not only improve the power quality and power supply capacity of the power system, but also increase the economic benefits and welfare of the whole society. In this work, a bi-level optimization model is proposed for the joint planning of substations and lines in looped urban distribution systems. The upper-level model aims to address the substation locating and sizing problem, whereas the lower-level model the network planning problem. Both the substations directly supplying power to a load and the contralateral substations that act as backup power source to the load are considered in the bi-level model. In order to solve the bi-level planning model which is mathematically mixed integer programing and with plenty of continuous and discrete variables, the bird swarm algorithm is improved and applied based on the idea of parallel computing of big data theory. Simulations on actual planning problems are employed to verify the effectiveness of the proposed bi-level distribution network planning model and the parallel bird swarm algorithm.

In the present work, high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) has been used for the identification of the major chemical constituents from the fruits of Sapindus mukorossi. A total of 31 peaks were identified based on their accurate masses and fragmentation characteristics. Among these 9 acyclic sesquiterpene oligoglycosides and 8 triterpenoid saponins were reported from the fruits of Sapindus mukorossi for the first time. This study demonstrates the potential of HPLC-ESI-QTOF-MS/MS for analysis and identification of acyclic sesquiterpene oligoglycosides and triterpenoid saponins.

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This research developed and optimized the methods for simultaneous determination of tetracycline (TCs), macrolide (MLs) and sulfonamide (SAs) antibiotics in soils using accelerated solvent extraction (ASE)- solid-phase extraction (SPE)-high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Methanol-citric acid (pH=4.7) was used as extraction solvent, diatomite (washed by EDTA) was used as dispersing agent. Firstly, soil was extracted by ASE with the parameter conditions: pressure 1500 psi, temperature 70°C, static 10 min, 1 circle, then pre-concentration by SPE and followed by HPLC-MS/MS analysis. Recovery was 86.3%~97.4% for SAs, 67.3%~87.4% for TCs and 68.4%~78.3% for MLs. RSD < 9 % and r > 0.99. Limits of detection (LOD) was 0.5~0.9 ug/kg for SAs, 0.2~1.1 ug/kg for TCs and 0.2~0.3 ug/kg for MLs. This method determined 9 kinds of antibiotics within 15 min, the determination accuracy can meet the requirements of actual analysis.