Magic wavelengths for the 6s^2\,^1S_0-6s6p\,^3P_1^o transition in ytterbium atom

The static and dynamic electric-dipole polarizabilities of the 6s^2\,^1S_0 and 6s6p\,^3P_1^o states of Yb are calculated by using the relativistic ab initio method. Focusing on the red detuning region to the 6s^2\,^1S_0-6s6p\,^3P_1^o transition, we find two magic wavelengths at 1035.7(2) nm and 612.9(2) nm for the 6s^2\,^1S_0-6s6p\,^3P_1^o, M_J=0 transition and three magic wavelengthes at 1517.68(6) nm, 1036.0(3) nm and 858(12) nm for the 6s^2\,^1S_0-6s6p\,^3P_1^o, M_J=\pm1 transitions. Such magic wavelengths are of particular interest for attaining the state-insensitive cooling, trapping, and quantum manipulation of neutral Yb atom.Comment: 13 pages, 3 figure

LED-Induced Fluorescence System for Tea Classification and Quality Assessment

A fluorescence system is developed by using several light emitting diodes (LEDs) with different wavelengths as excitation light sources. The fluorescence detection head consists of multi LED light sources and a multimode fiber for fluorescence collection, where the LEDs and the corresponding filters can be easily chosen to get appropriate excitation wavelengths for different applications. By analyzing fluorescence spectra with the principal component analysis method, the system is utilized in the classification of four types of green tea beverages and two types of black tea beverages. Qualities of the Xihu Longjing tea leaves of different grades, as well as the corresponding liquid tea samples, are studied to further investigate the ability and application of the system in the evaluation of classification/quality of tea and other foods

A study on investigating the thermal and energy saving performances of flat plate heat exchanges (FPHE) with different corrugated channels configurations

Du to scarce conventional energy resources, energy consumptions in the buildings occupied a large proportion of the overall energy consumptions. Therefore, many researchers pay more attentions to energy conservation in the buildings, including the heat recovery of air ventilation systems. Previous studies investigated the application of the plate heat exchangers in the heat recovery of air ventilation systems. The objective of this paper is to offer new methods to improve the thermal performance of heat recovery system and provide a guidance for the optimization design of a novel plate heat exchanger. This paper firstly compared the relevant results of numerical simulations with previous experimental results and verified the validation of the numerical simulations. Then, this paper used the Computational Fluid Dynamics (CFD) method to investigate the heat transfer characteristics and the pressure drop as well as the flow distributions in plate heat exchangers with two different corrugated surfaces (triangular and trapezoidal) and different heights of the channel spacing. In the paper, the numerical studies were carried out at a uniform wall heat flux, 580W/m2, for air as the working fluid. The Reynolds (Re) number varied from 500 to 2500 under three different channel heights and corrugated surfaces. The numerical results showed that, corrugated surfaces not only had a significant positive impact on heat transfer enhancement, but also led to an increase in the pressure drop through the channel. It can be seen that the effects of the corrugation patterns on the heat transfer and pressure drop were various for different channels with different Re numbers. In addition, the comparisons of comprehensive heat transfer factors identified that when the height of the channel spacing is larger, it is more appropriate to choose a triangular corrugated channel at a lower Re number. However, at a higher Re number, selecting the trapezoidal corrugated channel may be more suitable. Based on this study, it can be found that the plate heat exchangers with corrugated surfaces are of high efficiency and compactness. Therefore, a large amount of energy can be saved by using corrugated plate heat exchangers to recover heat

Systematic study of elliptic flow parameter in the relativistic nuclear collisions at RHIC and LHC energies

We employed the new issue of a parton and hadron cascade model PACIAE 2.1 to systematically investigate the charged particle elliptic flow parameter $v_2$ in the relativistic nuclear collisions at RHIC and LHC energies. With randomly sampling the transverse momentum $x$ and $y$ components of the particles generated in string fragmentation on the circumference of an ellipse instead of circle originally, the calculated charged particle $v_2(\eta)$ and $v_2(p_T)$ fairly reproduce the corresponding experimental data in the Au+Au/Pb+Pb collisions at $\sqrt{s_{NN}}$=0.2/2.76 TeV. In addition, the charged particle $v_2(\eta)$ and $v_2(p_T)$ in the p+p collisions at $\sqrt s$=7 TeV as well as in the p+Au/p+Pb collisions at $\sqrt{s_{NN}}$=0.2/5.02 TeV are predicted.Comment: 7 pages, 5 figure