An improved method for the determination of chemical oxygen demand (COD) is presented. This method is based on the standard method but using silver sulfate as a masking agent for the chloride and using the microwave for the digestion. The method gives tiny errors when the chloride of the samples increases from 606.6 mg/L to more than 30,000 mg/L. The method applies to the samples containing macromolecules and give better results when the sample is prehydrolysed.
This paper describes an adaptive control method for a magnetic drive actuator that used for the laser cutting to realize high speed and high accuracy machining. Firstly, a zero bias current method and a nonlinear compensator are examined and used for the actuator. Secondly, an adative control method is presented. Finally, the coefficient of the gap-current-force is estimated and the effectiveness of the presented control method is verified by experiments. The experimental results show that the coefficient of the gap-current-force reduces exponentially depending on the increase in the length of the air gap. By using the adaptive control, the peak-to-peak vibration amplitude of the lens holder is reduced from 1.95um to 1.55um.
This paper describes a precision control method for a magnetic drive actuator used for the laser cutting to realize high speed and high accuracy machining. Firstly, a zero bias current method is applied to drive the electromagnets to achieve a high-precision and long-stroke of the actuator. Secondly, a compensation method of the zero point of the displacement sensors is presented to prevent the generation of the disturbance force produced by the elastic hinges. Finally, the positioning performance of the actuator is evaluated through experiments and the experimental results show that the actuator has a positioning resolution of the order of micrometer, a bandwidth greater than 130Hz, and a positioning stroke of 1mm.
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