Simultaneous Determination of Fluorescein, Rhodamine 6G and Rhodamine B in Turbid Solution by Polarization Variable-Angle Synchronous Fluorescence Spectrometry

Polarization variable-angle synchronous fluorescence spectrometry was proposed to determine samples in turbid solution. A mixture of fluorescein, rhodamine 6G and rhodamine B was used to evaluate the technique. The background caused by scattering light was decreased remarkably. The limits of detection were 0.6 ng/ml for fluorescein, 2.3 ng/ml for rhodamine 6G and 4.1 ng/ml for rhodamine B, respectively.

REVERSE VARIABLE-ANGLE SYNCHRONOUS SPECTROFLUORIMETRY FOR RAPID SIMULTANEOUS DETERMINATION OF CHLOROPHYLL A AND CHLOROPHYLL B

Rapid simultaneous determination of chlorophyll a and chlorophyll b by reverse variable-angle synchronous spectrofluorimetry has been studied on a laboratory-constructed microcomputer-controlled versatile spectrofluorimeter.A method in estimation of scan parameters for the determination of two-component system by variable-angle synchronous spectrofluorimetry has been suggested

Multi-objective optimization of frequency and damping of vertical stabilizer skin structure placed with variable-angle tows

The vibration characteristics of composite vertical stabilizer skin structures play a critical role in damping effects designed for overcoming the air disturbances experienced by aircraft structural components during flight.The first-order fundamental frequencies and their corresponding damping characteristics of the vertical stabilizer skin structure tow-steered by automatic fiber placement technique were optimized with the parameterized trajectories and plies as design variables.Firstly,the vibration and damping numerical models were derived based on Kirchhoff laminate theory,the Rayleigh-Ritz method,and the Strain Energy Method.Then the optimization model was developed by adopting the self-adaptive Differential Evolution Multi-objective optimization algorithm and incorporating the solution method of Pareto Front.The constraints of this optimization model considered the experimentally obtained minimum turning radius of prepregs tow-steered in automatic fiber placement process obtained from experimental tests.Finally,the comparison of numerical simulation results was conducted for the optimized trajectories and the conventional straight trajectories under various boundary conditions,and the numerical results were partially validated through damping and frequency tests.The results indicate the vibration characteristics of the composite vertical stabilizer skin structure can be enhanced to a large extent by optimizing fiber trajectories,and the enhancement percentage is affected by the boundary conditions of the actual structure.

Effect of variable-angle trajectory structure on mechanical performance of CF/PEEK laminates made by robotic fiber placement

In comparison to the traditional fixed-angle trajectory,the variable-angle trajectory has a greater design space.However,it is a challenge to determine which common design curve structure is the most effective for improving mechanical performance.This work explores the effects of various design curves such as fixed-angle curve,linear curve,arc curve,sine curve,Bezier curve,and cubic polynomial curve trajectories on mechanical performance of laminates,including vibration modal performance and buckling performance.Genetic algorithm and improved NSGA-II algorithm are then used to optimize various curve structures.The results are confirmed utilizing thermoplastic Carbon Fiber(CF)/Polyether-Ether-Ketone(PEEK)laminates made by robotic fiber placement experiments.The relationship model between different mechanical performance and curve design variables is established.The optimization of variable-angle structure with mechanical properties as input variables is achieved.Meanwhile,a full-process angle-variable laying software platform from trajectory planning(CAD),trajectory optimization to manufacturing(CAM)is developed for facilitating the fiber placement application.