High-Efficiency(Over 10%) Parallel Tandem Dye-Sensitized Solar Cells Based on Tri-Carbon Electrodes

Ensuring high power conversion efficiency,partially or completely replacing Pt electrodes with inexpensive materials is one of the important development directions of dye-sensitized solar cells(DSSCs).In this work,we have developed a threecomponent(MWCNTs,carbon black and graphite) carbon(tri-carbon) electrode material for DSSC devices combined with the advantages of high electron transfer kinetics of MWCNTs,plentiful catalytic sites in crystal edges of carbon black and superior electrical conductivity and catalytic activity of graphite.Using a tri-carbon electrode,a Pt electrode,and two N719-sensitized photoanodes,a parallel tandem dye-sensitized solar cells are assembled obtaining a high PCE of 10.26%(V_(OC)=0.70 V,J_(SC)=19.99 mA/cm~2,FF=73.33%).It opens up a new avenue for the development of low-cost and highperformance DSSCs.

Sliding-Mode Control Based on Index control Law for MPPT in Photovoltaic Systems

A novel maximum power point tracking method based on sliding mode control and average state model of PV generation systems is developed.This method consists of two parts:term of constant control and term of index control.It is different from the conventional sliding mode control which uses a constant speed control law.The developed method uses a controllable sliding mode switching function which can automatically adjust the approaching speed,so as to enable the photovoltaic system to achieve fast dynamic response and stable output power.System simulations using MATLAB are performed.Compared with conventional methods,simulation results show that maximum power point tracking times for the novel method both in start-up phase and in cases of environmental changes can be shorten by more than 50%.A experimental platform of 150W PV system has been established to conduct tests.Experimental results show that the maximum power point tracking times both in start-up phase and in load stepping phase including the illumination change phase,can be significantly decreased.These results indicate that the developed method owns better dynamic response than constant speed control law.It can be used in photovoltaic generation system.

HPLC法测定林下山参制浆前后人参皂苷Re、Rg_1、Rb_1、Rg_3、Rh_1、Rh_2含量的变化

目的分析林下山参制浆后人参皂苷Re、Rg_1、Rb_1、Rg_3、Rh_1、Rh_2含量的变化情况。方法采用HPLC-UV法,Innoval ODS-2色谱柱(250 mm×4.6 mm,5μm);流动相为乙腈-水溶液进行梯度洗脱;柱温30℃;体积流量1.0 mL/min;进样体积20μL;检测波长203 nm。结果林下山参中6种人参皂苷Re、Rg_1、Rb_1、Rg_3、Rh_1、Rh_2质量分数分别由制浆前的0.651、0.506、0.363、0.014、0.023、0.031 mg/g变化为制浆后的0.517、0.413、0.105、0.122、0.214、0.098 mg/g。人参皂苷Re、Rg_1、Rb_1、Rg_3、Rh_1、Rh_2分别在2.5~100 mg/L具有良好的线性关系,r2均大于0.999 5;精密度、稳定性及重复性良好;平均加样回收率为95%~105%,RSD为1.25%~3.05%。结论林下山参中6种人参皂苷Re、Rg_1、Rb_1、Rg_3、Rh_1、Rh_2的含量在制浆前、后发生变化。林下山参制浆后人参皂苷Re、Rg_1、Rb_1的含量降低,稀有人参皂苷Rg_3、Rh_1、Rh_2的含量分别增高8.7、9.3、3.2倍。基于HPLC最佳分离参数建立的6种人参皂苷成分同时分析的方法具有较好的准确性和可靠性,可为林下山参浆的质量评价提供科学依据。