Effect of Valence Band Tail Width on the Open Circuit Voltage of P3HT:PCBM Bulk Heterojunction Solar Cell:AMPS-1D Simulation Study

The effect of the valence band tail width on the open circuit voltage of P3HT：PCBM bulk heterojunction solar cell is investigated by using the AMPS-1D computer program. An effective medium model with exponential valence and conduction band tail states is used to simulate the photovoltaic cell. The simulation result shows that the open circuit voltage depends Iinearly on the logarithm of the generation rate and the slope depends on the width of the valence band tail. The open circuit voltage decreases with the increasing width of the band tail. The dark and light ideality factors increase with the width of the valence band tail.

Numerical and Experimental Study of the 3D Effect on Connecting Arm of Vertical Axis Tidal Current Turbine

Vertical axis tidal current turbine is a promising device to extract energy from ocean current. One of the important components of the turbine is the connecting arm, which can bring about a significant effect on the pressure distribution along the span of the turbine blade, herein we call it 3D effect. However, so far the effect is rarely reported in the research, moreover, in numerical simulation. In the present study, a 3D numerical model of the turbine with the connecting arm was developed by using FLUENT software compiling the UDF（User Defined Function） command. The simulation results show that the pressure distribution along the span of blade with the connecting arm model is significantly different from those without the connecting arm. To facilitate the validation of numerical model, the laboratory experiment has been carried out by using three different types of NACA aerofoil connecting arm and circle section connecting arm. And results show that the turbine with NACA0012 connecting arm has the best start-up performance which is 0.346 m/s and the peak point of power conversion coefficient is around 0.33. A further study has been performed and a conclusion is drawn that the aerofoil and thickness of connecting arm are the most important factors on the power conversion coefficient of the vertical axis tidal current turbine.

Validation of the Ability of Full Configuration Interaction Quantum Monte Carlo for Studying the 2D Hubbard Model

To validate the ability of full configuration interaction quantum Monte Carlo （FCIQMC） for studying the 2D Hubbard model near half-filling regime, the ground state energies of a 4×44×4 square lattice system with various interaction strengths are calculated. It is found that the calculated results are in good agreement with those obtained by exact diagonalization （i.e., the exact values for a given basis set） when the population of psi particles （psips） is higher than the critical population required to correctly sample the ground state wave function. In addition, the variations of the average computational time per 20 Monte Carlo cycles with the coupling strength and the number of processors are also analyzed. The calculated results show that the computational efficiency of an FCIQMC calculation is mainly affected by the total population of psips and the communication between processors. These results can provide useful references for understanding the FCIQMC algorithm, studying the ground state properties of the 2D Hubbard model for the larger system size by the FCIQMC method and using a computational budget as effectively as possible.

STUDIES ON THE ASYMMETRIC DECOMPOSITION OF D,L-LEUCINE INDUCED BY ^(60)Co γ-IRRADIATION

Sublimed D-,L-,and DL-leucine under vacuum were subjected to ^(60)Co γ-irradiation with different doses.The enantiomeric compositions of samples were determined by chirasil- val capillary column gas chromatography,and the relative yields of radiolytic products(H_2, CO_2 and NH_3)were measured by packed column gas chromatography.The obtained data showed the peak area ratios D/L of DL-leucine after different absorbed doses of irradiation are all the same as that of samples with no irradiation,within the limit of error.So are the ratios for the separately irradiated D-and L-leuicne.This suggests that no asymmetric decom- position was found.The relative yields D/L of radiolytic products(H_2,CO_2 and NH_3)are very close to 1.00,indicating that the D-leucine cleavage rate was the same with that of the L-leucine.From the view of dissipative structure,an explanation for the result was presented.

Experimental study of cesium 5D+5D→6S+(nL=9D,11S,7F)energy pooling collisions

We report experimentally the measured rate coefficients for the energy pooling （EP） collisions process Cs（5D） ＋Cs（5D） →Cs（6S）＋Cs（nL = 9D, 11S, 7F） in cesium densities of 1016 -1017 cm^-3. The 5D state was populated via 8S →7P→ 5D spontaneous emission following two-step pumping 6S → 6P3/2→ 8S. Since the 5D → 6P （3.0-3.6 μm） fluorescence could not be detected in this experiment, we carried out a relative measurement for the process 6P W 5D → 6S W 7D. The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode laser beam, tuned to 6P3/2→9S1/2 transition, which could be translated parallelly to the pump beam. The excited atom densities have been combined with the measured fluorescence ratios to yield EP rate coefficients. The average values for nL = 9D, 11S and 7F are 8.0 ± 4.0, 7.0 ± 3.5, and 9.3 ± 4.6 （in units of 10^-10cm^3/s）, respectively. Influence of the energy transfer process 11S ＋ 6S ←→7F ＋ 6S on the rate coefficients k11s and k7F is also discussed.