An activated carbon‐geopolymer composite (ACGC) was prepared by using fly ash as raw materials via a simple geopolymerization process for treating the Pb(II) contaminant in wastewater and soil. The phase composition, microtopography, pore structure, and surface groups of the composites were studied by X‐ray diffractometer, field emission scanning electron microscopy, X‐ray photoelectron spectroscopy, N2 adsorption‐desorption isotherm, and Fourier transform infrared spectroscope. It was discovered that there was a synergistic effect between geopolymer matrix and activated carbon (AC), that is, addition of AC particles could increase the pores in geopolymer while strong alkalis condition provided by geopolymer enhanced the contents of oxygenic groups of AC. When the composite was used as the adsorbent, the sample containing 20 wt% AC (40ACGC) showed the maximum adsorption capacity (319.72 mg/g), and its adsorption isotherm fitted the Langmuir model well, suggesting the monolayer adsorption of Pb2+ on the 40ACGC. The kinetics of Pb2+ adsorption on the 40ACGC belonged to the pseudo‐second‐order model, indicating that Pb2+ adsorption on the composite followed chemical adsorption. In addition, the 40ACGC sample showed excellent stabilization performance for Pb2+ in soil. This work offered a new thinking to the application of geopolymers into remediation of heavy metal‐polluted soil.
Keywords: optical fibre winding tension control; angular speed trajectory planning; S-shaped acceleration and deceleration curve; starting and stopping of optical fibre winding.Abstract. The paper suggests a tension control method based on angular speed trajectory planning to improve tracking angular speed of fiber supply axis and precision of controlling optical fibre tension during the course of starting and stopping of optical fibre winding. First, kinematic trajectory of fibre extraction axis is planned according to five-stage S-shaped acceleration and deceleration curve; then angular speed trajectory of fiber supply axis is planned in a synchronized way according to established tension control system model to realize synchronized planning of active fibre retraction axis and passive fiber supply axis in the course of starting and stopping of optical fibre winding. Test of optical fibre winding acceleration course is conducted on quadripolar optical fibre winder. With this method, the average of tension on optical fibre is 25.0879g,standard deviation is 0.5218, overshoot is 7.53%, and tension's frequency within scope of ±1g is 94.11%. Compared with integral separating PID control method, this method has high precision in tension control, small overshoot, small tension fluctuation. Applicable to various types of optical fibre winder and spooling equipment, this method has higher theoretical significance and engineering application value.
Abstract4 novel instrument has been designed and implemented to measure and analyze the real-time current and voltage of sudden change, which often occurs at the startup of motors. This paper gives the algorithm for eliminating errors in rms value estimations end the algorithm for compensating voltage varying. The digitized signals are sent to a PC directly through an EPP (Enhanced Parallel Port), so neither the special communication interface nor addition buffers are needed. That makes the instrument simple in realization and convenient for use. With Hall effect probes, this instrument can measure currents as high as 6000 amps fast and accurately. The measured values can be displayed either in real-time waveforms or in R.M.S. value curves according to the user's choice.
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